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PAPER 

ON 

BUILDING STONES. 

BY 

C H. PORTER, M.D. 









PAPE R 


ON 


BUILDING STONES. 



CHARLES H. PORTER, M.D. 




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ALBANY: 

J 0 E L M UNSELL. 

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Albany, N. Y., May 12, 1868. 


Hon. Hamilton Harris , 

Chairman of The New Capitol Commission. 

Sir : 

Some mouths since in conversation with the Hon. J. V. L. Pruyn, 
a member of your Commission, regarding the proposed New Capi¬ 
tol, allusion was made to the difficulties attending the proper 
selection of building materials, and I was asked to express in writing 
my views upon the subject. 

Believing that a comprehensive review of this matter, though it 
be but brief, may possibly be beneficial, in directing your attention 
to certain important points, I have taken pleasure in preparing the 
following statement. 

It exhibits the essential differences between good and bad build¬ 
ing stones, the causes of their deterioration, and the means that may 
be adopted for determining their comparative value, and thereby 
of selecting those most proper for architectural purposes. 

Very respectfully, 

Your obedient servant, 

Ciias. H. Porter. 















t 


NOTES ON BUILDING STONES. 


I. Errors made in selecting Building Stones. 

II. General Character of Building Stones. 

+ 

III. Causes of tiie Destruction of Stones in Buildings. 
IY. Determination of the Comparative Value of Build¬ 


ing Stones. 


















NOTES ON BUILDING STONES. 


I. ERRORS MADE IN SELECTING BUILDING STONES. 

a. General considerations. 

The importance of selecting proper materials for con¬ 
structing public edifices, is so evident, that it needs but 
the statement of the fact, without argument, to have it 
generally accepted. 

It is plain that in the construction of public buildings, 
care ought to be taken to have them, not only convenient 
and proper places for the transaction of business, and of 
such architectural design, as to present an agreeable im¬ 
pression to the eye, but, as they are intended for future 
generations as well as for the present, they should be of 
such material, as to withstand, as far as may be, the destruc¬ 
tive effects of time. 

They should be, in fact, both in architecture and material, 
representatives of the highest skill and greatest knowledge 
of the age which produces them. 

That there exist great difficulties in making proper selec¬ 
tions of building material, and that it is not merely a 
scientific refinement that finds infinitesimal defects and dif¬ 
ferences and magnifies them, will it is thought be apparent 
on a brief consideration of the subject. 

Even a limited examination of edifices, public and pri¬ 
vate, discloses the fact, that building stones of the same 
general character vary greatly in durability. While some 
richly embellished with carved ornamentations, preserve 







8 


NOTES ON BUILDING STONES. 


their finest lines and traceries unimpaired, after years and 
even centuries of exposure, others quickly show signs of 
decay and rapidly crumble, requiring continual repairs to 
keep them in proper condition. 

Again in some buildings, blocks of stone are found with 
cracks and fissures in them, the material not being in all 
cases of sufficient strength to resist the superincumbent 
pressure; in other buildings a similar variety of material, 
though subjected to equal or greater pressure, remains 
unimpaired. 

While the above is evident of the same kinds of stones, 
there is even a greater difference between the different kinds. 
In Europe, this subject can be more fully illustrated than 
here, from the fact that there may he seen public edifices 
of various ages, from those erected during the present 
century, to those many hundreds of years old. 

In our own country it is different, our public buildings 
are new, few of them are a century old, and the larger por¬ 
tion have been erected during the present century, still even 
on them where time has had but a few years to exert his 
force, his destructive effects are seen, and to an extent 
which is as surprising as it is unpleasant. 


b. Examples of the selection of improper building materials. 

If anywhere, one would expect to find in the govern¬ 
ment buildings at Washington, strength and durability, 
as well as elegance and beauty. If it is assumed that the 
latter are present, certainly in the former particulars, they 
are woful failures. 

Some of them, are indeed examples of large expendi¬ 
tures of money in erecting structures of totally unsuitable 
material, and this without even the excuse of present 
economy, for the cost was not less than that of srood and 
durable material. 









NOTES ON BUILDING STONES. 


9 


The destruction of building material is exemplified in a 
remarkable degree in the Old Capitol. In the report of 
the secretary of the interior to congress in 1849, it is 
stated, that some of the stones near the base of the build¬ 
ing were deeply affected, so that it was necessary to 
remove them. The stones rapidly absorbed water which 
condensed upon them, and the natural cement that held the 
particles together appeared to be dissolved, causing the 
material to crumble. In the words of the report, “ If 
left wholly unprotected from atmospheric influences for 
one-third of the time that marble structures are known to 
have stood, the noble structure would become a mound of 
sand.” 

The Treasury and Patent Office buildings are of the 
same material, and having been in no manner protected 
show very serious evidences of decay. 

The brown sandstones, so largely used of late years, 
both for public and private edifices, furnish other exam¬ 
ples of the same fact. In a large number of private houses 
faced with this material, more or less decay is evident. In 
some, the surfaces are worn and roughened, and the angles 
rounded; in others where the blocks have been but a few 
years in walls, the mass is so disintegrated — the binding 
material seeming to have disappeared—that they may 
readily be penetrated by a sharp knife. 

The basement of the City Hall in Hew York, is of a 
poor variety and is rapidly crumbling, while Trinity Church 
in the same city and the Boston Athenreum, although of a 
similar but superior material, remain unaffected. 

The more or less destructive action of atmospheric agen¬ 
cies on marbles, may be seen in almost any city. The 
State Ilall in Albany furnishes an example, although but 
twenty-eight years have passed since it was completed 
(1840), the solid angles of the exposed blocks are rounded, 
the surfaces are roughened, and a very slight force with the 




10 


t 


NOTES ON BUILDING STONES. 


lingers is sometimes sufficient to detach small portions of 
the stone. The weathering has been so great, that already 
portions of the crumbling material of the walls have been 
replaced, and the front steps have been renewed or exten¬ 
sively repaired once, if not twice, within the last ten years. 

The Albany City Hall was completed in 1832; already 
the front of its portico shows numerous cracks and fissures, 
that may well claim serious consideration. A block in the 
upper part of the northwest corner is so much broken 
down by the action of the weather, as to require imme¬ 
diate renewal; other blocks have deteriorated, but to a less 
degree. 

Oftentimes beside the roughening of surfaces, flaking 
off of sheets and rounding of angles, dark streaks and 
stains disfigure the surfaces of buildings owing to the 
presence of iron in the stones of which they are composed. 

In Hew York city, where marbles of a dolomitic variety 
have lately been largely employed, many buildings even 
now show signs of decay, and although but seldom of a 
very decided character, it is apparently only because they 
have been exposed but a few years. 

Every cemetery furnishes examples of the striking dif¬ 
ferences in the durability of marbles and other stones — 
some monuments retaining their color, and finest lines 
and enrichments unimpaired, while others are roughened 
and stained by iron, and frequently disfigured with patches 
of vegetable mould, though erected within a decade. 

The national monument at Washington is another 
example of a poor selection of material: the marble yields 
so readily to pressure, that in all probability it would be 
crushed by its own weight, before it could be completed. 

The Washington monument at Baltimore is also of 
poor material. In 1850, only twenty-one years after its 
completion, Prof. W. R. Johnson found numerous cracks 
and fissures in it. In the northeast side, a crack com- 







NOTES ON BUILDING STONES. 


11 


menced near the bottom, and followed the joints and 
partially transverse or vertical cracks crossing the blocks of 
marble. The 3d, 5th, 8th, 10th, 11th, 13th, 14tli, and 15th 
courses of stone, counting from the bottom, were seen to 
be broken, either partially or wholly across, and in one 
instance a block was found broken into three pieces. On 
the southeast side was a second line of fracture, crossing 
ten or twelve blocks. On the southwest side, fifteen 
blocks were cracked, either partially or wholly across. 
On the west side a fourth line of fracture appeared to 
ascend forty or fifty feet, and on the southwest side a fifth 
line of fracture was observed. 


c . Conclusions from the above. 

The examples which have been mentioned, besides others 
which will readily occur, to those who have directed their 
attention to this subject, render it evident, that while the 
beauty of a building stone, or its suitability, as regards its 
color, texture, etc., may readily be determined, it is by no 
means the case, with its strength and durability, which 
vary much and depend upon causes not visible to the eye. 

Indeed it must be admitted not only that, IsL Building 
stones of the same , as well as of different varieties , vary greatly 
in quality , but also that, 2d. Ordinary observation has not 
hitherto proved sufficient to ensure a proper selection of building 
stones. 

In order that just ideas may be entertained, it is advisa¬ 
ble to consider the general character of and the essential 
difference between building stones, in order to appreciate 
the causes which render some more suitable than others 
for architectural purposes. 


12 


NOTES ON BUILDING STONES. 


II. GENERAL CHARACTER OF BUILDING STONES. 

The value of a building stone may he briefly expressed 
as depending upon two causes: 

1st. Its physical constitution; and 2d. Its chemical com¬ 
position. 


1st. Physical Constitution. 

Without going into minute details we may remark 
briefly on the following points: 

a. Size of the constituent 'particles. 

In the compound stones the different mineral elements 
occur in particles of various sizes. Thus in most traps, 
the mineral elements are not separately distinguishable, hut 
form a homogenous mass. In some granites, the particles 
of feldspar, quartz and mica are so small that the stone has 
a fine even texture, and appears of an almost uniform 
color, although the minerals of which it is composed 
differ in this respect. In others the particles are larger, 
and the different constituents may be readily recognized. 

Many varieties of sandstones are perfectly uniform in 
texture, while others contain grains of sand and pebbles of 
various sizes. The marbles differ as widely, the crystalline 
grains in some being coarse like alum, in others fine 
resembling loaf sugar. 

These differences are often so considerable as to seriously 
affect their durability, and to produce in the case of the 
compound stones, great difference in the case of working 
them, and of producing a smooth or finished face. 

It has long been the belief among practical men that 
coarsely crystalized stones are inferior in strength to fine 
grained ones of the same character. 


NOTES ON BUILDING STONES. 


13 


Experiments made with stones of the same variety, and 
of similar chemical composition and specific gravity, have 
demonstrated this opinion to be correct. It is clearly 
shown in the following table of Prof. Johnson: 

TABLE I. 

Resistance to compression of coarse and fine grained stones 
of the same varieties , of the dimensions of one cubic inch. 


Stones. Weight in pounds required 

to crush. 

lloussard stone, coarse grain. 3,957 

Choni de Yilleburg, fine grain... 8,300 

Saillon Court House, coarse grain. 2,062 

Passy and Vairgirard, fine grain. 4,484 

Symington coarse grained marble. 2,334 

Symington fine grained marble... 4,434 

Alum limestone, coarse grained marble, highest result 2,968 
Fine grained marble . 6.344 


Average of the four coarse grained stones. 2,830 

Average of the four fine grained stones. 5,983 

The ratio being as 100 to 211. 


b. Porosity. 

In no respect do stones differ more than in the mode of 
the arrangement of their particles, and this as well with 
those having a crystalline as those having a fragmental 
structure. 

Most, as the traps and basalts, have their particles so 
closely compacted together, as to he free from sensible 
pores. Others, on the contrary, as many sandstones, lime¬ 
stones, etc., are imperfectly compacted; they have a porous 
or cellular structure; they readily absorb water, and this 
oftentimes proves a cause of disintegration. 












14 


NOTES ON BUILDING STONES. 


Thus while carbonate of lime in its various forms is 
commonly regarded as a readily perishable material, some 
of the more compact varieties of marble and limestone 
resist the destructive action of frost to a surprising degree, 
being in this respect superior to many granites, as well 
also as to most of the sandstones. 

But all stones absorb water, even the most homogenous 
and compact; the difference between them in this respect 
is only one of degree. 


c. Cohesion. 

Stones differ greatly in the firmness with which their 
particles are hound together. Thus among the granites 
may be found many which break down upon the applica¬ 
tion of a slight force, while the greater portion of them 
withstand a great pressure. Even with those granites 
used for building purposes, some are more than five times 
the strength of others. And among the marbles, some 
are crushed by a weight one-third of that which others 
resist. 

The same is true of the sandstones, and even greater 
differences are found in other materials. 

It is to be particularly noted that the resistance of a 
stone to pressure is dependent on its state of aggregation 
and not on the density or hardness of its particles; thus 
the silicious particles composing sandstones, have a hard¬ 
ness of 7, and yet frequently blocks of this material are 
far weaker than marbles which have a hardness of about 3. 

Resistance of a stone to wear depends upon toughness 
rather than hardness, and is not immediately connected 
with its power of resisting pressure. Thus the crushing 
weight of Portland stone, being represented by 1,000, that 
of York is 1,200, yet in many cases Portland steps will last 
longer than York. The crushing weight of Peterhead 


NOTES ON BUILDING STONES. 


15 


granite is represented by 1,800, not quite double that of 
Portland stone, but, it is said, if used as a street paving, it 
will outlast six sets of the latter. 

2d. Chemical Composition. 
a* General chemical composition. 

The different minerals are compounds of definite com¬ 
position, varying, however, in accordance with known laws. 
These variations oftentimes are of importance. The gran¬ 
ites are ordinarily very durable, but those whose feldspar 
contains the larger proportion of alkali are more liable to 
decomposition than others. So also the granites in which 
feldspar predominates are particularly apt to crumble. 

Again, the marbles may be mentioned; the true marble 
is a pure crystalline carbonate of lime, but oftentimes 
marbles contain carbonate of magnesia in various propor¬ 
tions. These latter are called dolomites, or dolomitic 
marbles; they vary exceedingly in their power of resisting 
atmospheric influences. 

Thus in England the choir of Southwell Church built 
of a magnesian limestone in the twelfth century, was 
found (1837) to be in so perfect a state “ that its mouldings 
and carved enrichments were as sharp as when first exe¬ 
cuted,” while other structures built of a similar material 
in the present century are rapidly going to decay. 

The commissioners appointed by the British parliament 
to investigate the qualities of the various building stones 
of the kingdom say, that “ so far as our observation extends 
in proportion as the stone employed in magnesian lime¬ 
stone buildings is crystalline, so does it appear to have 
resisted the decomposing effects of the weather.” 

Prof. Daniels, however, observes that from the result of 
experiments “the nearer the dolomites approach to equiva¬ 
lent proportions of carbonate of lime and carbonate of 


16 


NOTES ON BUILDING STONES. 


magnesia, the more crystalline and better they are in 
every respect.” 

Though properly coming under this head, we have 
thought best to consider in a separate section, 


b. Cementing materials. 

The binding material or the substance cementing the 
particles together, is often of the same nature as the 
particles themselves, as in the marbles, certain sandstones, 
etc. At other times it is different, as in many sandstones : 
the cement being sometimes silicious, at other times 
ferruginous or calcareous, and frequently having a mixed 
character. 

When the cement is calcareous, the stone is likely to be 
more readily disintegrated than when it is silicious, owing 
to its being more easily soluble, and thus the stone may 
gradually crumble away, being continually assisted by the 
increasing porosity of the surfaces. It was probably largely 
owing to the gradual removal of the cement, that the 
stone of the Old Capitol, Treasury and Patent Office 
buildings so rapidly disintegrated. 

On the contrary, when the sandstone has a ferruginous 
or silicious cement, other things being equal, the stone 
will probably be more durable. TIence it is, that certain 
varieties of sandstones, long known and extensively used, 
still maintain a high character. 

Melrose Abbey and Glasgow Cathedral, though built in 
the 12tli century, are yet in a fine state of preservation. 

It may be mentioned as an interesting fact that many 
stones, granites as well as sandstones, limestones, etc., 
though soft and easily worked when recently quarried, 
harden by exposure to the air. The explanation of this 
fact is incomplete; it probably depends upon both physical 
and chemical causes. 


NOTES ON BUILDING STONES. 


17 


c. Foreign Ingredients . 

By this term is meant those substances present in a 
stone but not essential to it. 

Thus marbles, carbonate of lime of a crystalline granu¬ 
lar texture often contain talc or mica and frequently iron 
pyrites, serpentine or silicious particles, as well as other 
minerals. Sandstones with a silicious cement sometimes 
contain iron pyrites and carbonate of lime and the same 
is true of other stones. 

Oftentimes these foreign ingredients exercise no inju¬ 
rious effect, at other times they render the material 
entirely unlit for architectural purposes. An example or 
two will suffice to illustrate this point. In many stones, 
if iron in a low state of oxydation be present, by the 
action of the oxygen and carbonic acid of the air, per-oxyd 
of iron (iron rust) is produced, and if the stone be light 
colored brownish red stains and streaks will appear, while 
at the same time the porosity of the stone will be increased. 
Again if iron pyrites occur in a marble or limestone, the 
same agencies may result in the production of sulphuric 
acid, which reacting on the carbonate of lime, will gradu¬ 
ally change its color and injure its texture, causing it 
rapidly to crumble. 

Sandstones containing carbonate of lime and iron pyrites 
undergo the same series of changes, and the effect is simi¬ 
larly disastrous. If iron pyrites is present in granites and 
other compound stones, as it decomposes it rusts the 
surface, loosening the grains, causingthe rock to fall to pieces. 

The presence of foreign ingredients in the clay used for 
bricks is frequently disastrous. Thus when vegetable 
fibres are present, they are consumed during the burning, 
leaving corresponding cavities, giving the bricks an open 
porous structure and rendering it of unequal strength in 
different parts. 


3 


18 


NOTES ON BUILDING STONES. 


The occurrence of fragments of limestone, or other 
calcareous matter, occasion the destruction of bricks, 
owing to the formation of caustic lime during the burning. 
When the brick becomes moistened the lime slakes, and 
tears it in pieces. As in the case of natural building stones, 
so also with bricks, the presence of foreign ingredients 
which are readily soluble, or which are rendered so by 
exposure is deleterious. They sometimes cause the brick 
to break down, as if it was gradually slaked, and always 
diminish its durability. 

There is sometimes found upon the walls of brick build¬ 
ings, as well as those constructed of certain stones, patches 
of a whitish color, which might at first sight be mistaken 
for vegetable mould. A closer examination reveals the 
fact, that these patches are composed of a multitude of 
minute crystals, and that chemically they are compounds of 
the alkalies or of lime and magnesia. 

These salts (either present originally, or produced by 
atmospheric causes upon the bases occuring in the stone), 
are gradually disolved by the moisture, and with it 
brought to the surface by capillary attraction. As the 
moisture is dissipated, the salts are left upon the surface. 
The presence of such substances is not only unfortunate 
as seriously disfiguring the appearance of the building, 
but further as indicating a porosity and a chemical cha¬ 
racter in the brick or stone, that is certain materially to 
diminish the durability of the edifice. 

An interesting example of the effioresence described, 
may be observed upon the walls of the Vassar Female 
College, Poughkeepsie, Y. Y. Two kinds of brick were 
used in the construction of these buildings, viz, the hard 
“Hudson lliver brick,” and the “Adams sand brick.” 
Yo eflloresence ever appeared on the former, but there 
has always been more or less on the latter. It varies in 
quantity, and in the area of the spots, coming and going 


NOTES ON BUILDING STONES. 


19 


with variations of temperature and humidity, hut finally 
disappearing entirely, sometimes in the second year after 
building. If, however, the walls become saturated with 
moisture, as by a leak in the gutter, the efflorescence 
reappears. It disappears latest from those parts of the 
walls which are protected from the rain, as under the 
cornices. The efflorescence consists principally of com¬ 
pounds of potash and soda. 

It must he remarked that the reactions and changes 
mentioned in this section are generally increased by varia¬ 
tions in temperature and alternate dryness and humidity. 

We may now consider the 


III. CAUSES OF THE DESTRUCTION OF STONES IN 

BUILDINGS. 

Under the heads of Is/. Physical Causes , and 2d. Chemical 
Causes . 


1st. Physical Causes. 
a. Inherent Weakness. 

In public edifices of large size and frequently towering 
to a great height, the pressure which the lower courses of 
stone sustain is often enormous. This is clearly shown in 
the following table: 


20 


NOTES ON BUILDING STONES. 


TABLE II. 


Weights actually home upon the square foot and square inch 
in certain buildings. 


Pressure on each 

Buildings. square loot in 

pounds. 

1 Pillars of church of All Saints, Angers 

(Forneaux stone),. 86.000 

2 Pillars of dome of Pantheon, Paris 

(Bayneaux stone),. 60,000 

3 Pillar in centre of Chapter House, 

Elgin (Bed Sand stone), . 40,000 

4 Piers under dome of St. Paul’s, Lou¬ 

don (Portland stone),. 39,000 

5 Piers under dome of St. Peter’s at 

Borne, . 33.000 

6 Keystone of arch of bridge of Neuilly 

i 

(Saillancourt stone),. 18,000 


Pressure on each 
square inch in 
pounds. 


597.22 

416.66 

277.77 

270.82 


229.16 


125.00 


In a few structures, the stones have cracked before the 
buildings have approached completion, in others the edi¬ 
fices at first apparently sound, after a time show fissures 
and seams. 

The effect, it is evident, in both cases is owing to the 
inherent weakness of the stone, it may not at once appear, 
but is gradually developed in accordance with the law that 

When any material is strained beyond a certain extent, 
each time that the pressure is increased to that degree, or 
if it is continued at that degree, there is a permanent 
derangement of the structure of the material, which will 
eventually increase to such an extent, that the parts 
separate. 

The strain which produces this permanent derangement 
in the structure of materials, varies from one-fourth to 
three-fifths of that which would directly destroy its cohesion. 

On account of the many defects of stone, and the 








NOTES ON BUILDING STONES. 


21 


different qualities of that from the same quarry, it is not 
considered prudent ordinarily to subject a stone to more 
than one-eiglith of its crushing weight. 


b. Improper Position. 

While many building stones are massive like granites, 
breaking one way about as readily as in others, others on 
the contrary have a laminated structure. The latter may 
be represented as consisting of a number of leaves joined 
together. 

A common error is to set the stone with its laminae or 
“bed ” in a vertical instead of a horizontal direction. As a 
consequence the action of the weather will often cause the 
laminae to scale off, “just as the leaves of a book will fall 
over if the volume be placed on the back, in an upright 
position.” 

This obvious error is to be met with frequently in public 
and private edifices, and notably in those faced with 
brown stone. It is so apparent in some cases as to strike 
the attention of a careless observer, especially where, as is 
often the case, one block of stone will be almost perfect, 
while that immediately adjoining has scaled off, and has 
its corners rounded, the difference being due simply to the 
relative position of their laminse in the wall. The cracks 
which appear in the pedestals of some of the columns in 
the State House are principally owing to the stones not 
being placed with their lines of stratification in a horizontal 
position. 


c. Alternate Freezing and Thawing. 

The changes of temperature, which the stones of build¬ 
ings undergo, cause a slight motion among the particles 
of which they are composed. The Bunker Hill monu- 


NOTES ON BUILDING STONES. 


09 

-J -J 


ment as Horsford lias shown, is scarcely ever at rest, from 
bending and warping under the influence of the varying 
temperature of its different sides. The disintegrating 
effect of this molecular motion would he unappreciable 
were it not combined with alternate freezing and thawing. 

The water which gets into the pores and fissures or 
between the laminae, being subjected to cold freezes, and 
afterwards by heat thaws. 

During congelation, the water expands, as the crystals 
of ice are forming, which tends to tear the particles of 
stone from one another. This action continuing for a 
series of years, results in more or less disintegration, it 
being apparently more considerable in the more porous 
and less firmly aggregated stones. This cause is probably 
one of the most active agents of decay. 

Another cause that under certain circumstances may 
exert an appreciable inflence is 

d. The Attrition of Silicious Dust, 

Blown by the winds and washed by the rains upon the 
building. 

2d. Chemical Causes. 

The chief among the causes which may be attributed to 
chemical influences is the 

a. Solvent Action of Water. 

Pure water as might be supposed has but little solvent 
power upon building stones; but when holding carbonic 
acid in solution, as it always does in nature, it is a much 
more energetic agent, especially upon limestones, marbles, 
and upon other stones of which carbonate of lime forms a 
part, as the calcareous sandstones. 


NOTES ON BUILDING STONES. 


23 


The continued action of this solvent may gradually pro¬ 
duce an effect, it probably being more considerable as the 
stone is more porous. Water bolding carbonic acid in 
solution, combined with alternate freezing and thawing, 
produces in most cases, in all probability the greater part 
of the disastrous effects already mentioned. 

b. The Oxydizing Influence of the Air , 

Often exerts a decidedly injurious influence, especially 
upon those materials containing pyrites or iron in a low 
state of oxydation. This point has already been referred 
to when treating of the foreign ingredients of stone, and 
need not be repeated. 


c. Flashes of Lightning . 

By every flash of lightning, nitric acid (aqua-fortis), is 
produced; this is a powerful solvent and carried upon the 
stones by rains must exert its influence. 

What are the inductive effects of electricity under such 
circumstances in producing chemical changes on the moist 
wall is not known, but it is probable that it may be 
injurious. 


d. Sulphur Acids produced from Coals. 

This is an active element of decay which has not 
hitherto been so much regarded, as its importance would 
seem to demand. 

The combustion of coals containing sulphur, results in 
the production of sulphurous acid, which in great pro¬ 
portion is finally converted into sulphuric acid (oil of 
vitriol). These acids exercise a destructive action on 
building materials, especially those containing lime or 


24 


NOTES ON BUILDING STONES. 


magnesia, as our marbles, limestones, etc., producing sul¬ 
phate of lime and magnesia. 

As coal seldom containes less than one-half per cent of 
sulphur, and frequently one per cent or more, every ton 
of coal when burned produces from thirty (30) to sixty (60) 
pounds of oil of vitriol. When one considers the enor¬ 
mous quantities of coal that are consumed in cities and 
the correspondingly great quantities of this corrosive 
agent that are thus disseminated in the atmosphere, we 
would naturally expect to find appreciable evidence of 
its effects on building stones, nor are we mistaken in this 
supposition, as the history of the new Houses of Parlia¬ 
ment (England), and other edifices show. After careful 
examination of various materials, the commissioners ap¬ 
pointed by the British parliament, selected a magnesian 
limestone from Bolsover Moor for the new edifices, it 
having been largely used for building purposes and with 
the best results. Even after an exposure of eight hundred 
years, as in Southwell church, the carvings were as perfect 
as when first executed. But in London, owing to the 
different conditions in which it was placed, it rapidly 
decayed, and artificial measures were resorted to to pre¬ 
vent further disintegration. 

J. Spiller in an article on this subject read before the 
British association for the advancement of science, at the 
Dundee meeting, September, 1867, thus remarks of the 
new Houses of Parliament. “In many places the disinte¬ 
grated stones exhibits white crystals of the sulphate of 
magnesia, which alternately dissolving and recrystalizing in 
the pores of the stone, may be conceived to exert a disrup¬ 
tive action sufficient to account for the scaling and fracture 
of the dolomite which has been so often made the subject 
of complaint and regret/’ And again, “ a close examina¬ 
tion of the circumstances attending the decay of stone at 
the Houses of Parliament invariably show an increased 


NOTES ON BUILDING STONES. 


25 


liability to corrosion under the projecting eaves and 
mouldings, and at such sheltered parts of the stone surface 
as are usually covered with soot and dust, and are in a 
position to retain for the longest period the moisture ab¬ 
sorbed during a season of rain.” Again he says, “ I have 
tested numerous samples of dolomite, Caen, Bath and 
Portland stones fresh from the quarry and in no instance 
found more than a trace of ready formed sulphate, whereas 
scrapings taken from the decayed portions of the stone of 
the new Palace at Westminster are bitter to the taste in 
consequence of the comparatively large amount of sulphate 
of magnesia formed during a few years exposure to the 
sulphurous gases occurring in a metropolitan atmosphere.” 

He remarks further that the decayed portions of Caen 
stone of Horthfleet College and St. John’s church, Wool¬ 
wich, contained respectively 3.4, and 4.6 per cent of 
sulphate of lime, while the interior portions of the same 
stone contained none of this material. 

e. Vegetation of Microscopic Lichens and Mosses. 

The seeds of these floating in the atmosphere are depo¬ 
sited upon the roughened stone, and may there germinate. 
Their minute fibres penetrate the interstices, separate the 
particles, and assist other causes in hastening decay, both 
mechanically and by the chemical changes taking place 
during their growth and dissolution. They also, at the 
same time, discolor the stone. These vegetations on 
buildings often prove a very serious evil, they are particu¬ 
larly frequent in low damp places and in moist climates. 

/. Locality A ffecting the Durability of Stone. 

Change of location often implies change of circum¬ 
stances, chemical as well as physical. Many stones which 
have stood the stress of ages in their natural site, will 
gradually be destroyed when placed in other localities.* 

4 


I 


26 


NOTES ON BUILDING STONES. 


For example, “ Caen stone endures well in Lower Nor¬ 
mandy, but decays rapidly in Havre and London.” The 
front of Buckingham Palace is constructed of a variety 
of this material. It there rapidly deteriorated to such an 
extent that it became necessary to paint its exposed 
surfaces. The same was the case with Lincoln’s Inn 
Library and other structures. 

The Bolsover Moor magnesian limestone as has been 
stated decays rapidly in London, but in other localities has 
remained unaffected by centuries of exposure. 

“ Some stones which are injuriously affected by a salt 
water atmosphere, stand well in the interior. Others which 
are very durable when wet or dry, give way when exposed 
to continual changes.” These examples illustrate the neces¬ 
sity of paying attention to the peculiar conditions to which 
the stones selected for public edifices are to be exposed. 

Having considered the nature of building stones and the 
chief causes which determine their deterioration, we have 
lastly to consider the means that may be resorted to for the 


IV. DETERMINATION OF THE COMPARATIVE VALUE 

OF BUILDING STONES. 

Before remarking on the particular modes to be em- 
ploved for the determination of the value of building 
stones, it is important to consider the following points: 

(1). A simple inspection of many marble and other 
quarries shows that not only is there a perceptible differ¬ 
ence in the stone of different layers, but also in that of 
various parts of the same layer. This difference may be 
only in color, but frequently also there is a marked differ¬ 
ence in texture, strength and composition. As then both 
the physical and chemical character of a stone may vary 
greatly in different parts of the same quarry, an examina¬ 
tion of a single piece is by no means satisfactory as finally 


NOTES ON BUILDING STONES. 


27 


determining the real value of the quarry as a source of 
building material. To ascertain the probable average 
quality of the stone, a number of examinations must 
be made of portions selected from different parts, and 
especially is this precaution necessary when different layers 
are to be employed. 

(2). To avoid errors arising from prejudice or other 
causes, it seems most proper that the specimens to be 
examined should be marked by the commissioners with 
numbers or in any proper way, but not with the locality 
from which they came. 

The results as furnished by the Examiner would then 
be free from any cause of suspicion, which otherwise might 
naturally arise, among those quarry men whose material 
was not finallv selected. 

a . Examination of the Material in Place. 

The rocks are the creation of past geological ages, and 
have been exposed to atmospheric and aqueous influences, 
to heat and cold, to pressure and changes of position, as 
well as to other decomposing and disintegrating agencies, 
for periods in comparison with which the oldest works of 
man are but as a day. Hence if we would acertain how 
the different rocks are affected by such causes they must 
be examined in their original location. 

In some cases, there will be found angular cliffs, tower¬ 
ing high above the earth, their edges and angles sharp, 
and their surfaces seeming as if recently exposed. Such 
appearances it is plain, are favorable indications of dura¬ 
bility. 

On the contrary, other rocks are met with as broad, 
roughened and rounded masses, scarcely rising above or 
even concealed beneath the surface by the debris resulting 
from their own decomposition. Their surfaces may be fur¬ 
rowed by water channels and by other irregular depressions. 


28 


NOTES ON BUILDING STONES. 


The brownish stains of iron may be present, and oxyd 
of iron and pyrites filling cavities and fissures, together 
with other indications of a poor and variable material. 
Such rocks it is evident should be avoided. 

General conclusions regarding the comparative dura¬ 
bility of different varieties of stone may be drawn from 
such observations. But the information thus furnished is 
by no means satisfactory as regards varieties pf the same 
stone. The marbles, for example, of different localities 
may have been exposed to different or unequal destructive 
actions during long geological periods, so that those which 
appear more worn, would under equal conditions prove 
the more durable. 

These considerations are sufficient to indicate that while 
such examinations are important, they are usually by no 
means conclusive, and often may give rise to serious error. 


b. Ancient Structures. 

Evidence of a similar character, but much more valuable, 
may be obtained by careful examination of old edifices, 
built of the materials under consideration. The evidence 
being the more satisfactory, as the structures are the more 
ancient and the locality the same as that in which the new 
buildings are to be erected. 

In our own country, valuable evidence of this kind is 
only obtainable in a few cases, as most of our buildings 
have been erected within a comparatively recent period. 

As the evidence that may be obtained by the means just 
mentioned is in most cases incomplete, and as often, it is 
almost wanting, recourse has been had to experiment to 
furnish the required information. 


c. Resistance to Pressure. 

The most important in its results of all experiments 
regarding building materials is the determination of the 


NOTES ON BUILDING STONES. 


29 


force required to crush them. The means resorted to for 
this purpose need not he given in detail. Suffice it to say 
that the apparatus consists essentially of a hydraulic or 
other press. It is so constructed, that when a cube of the 
material to be tested is placed in it, pressure may he 
gradually applied until the cube gives way. The machine 
is so arranged that the force required to produce this effect 
is capable of accurate determination. 

The importance of determining the resistance of build¬ 
ing materials to pressure, cannot well be overestimated. It 
gives accurate information obtainable in no other way. It 
enables us to make a classification of building materials ac¬ 
cording to one of their most vital qualities, so that those 
which are weak need not be placed where strength is 
required. 

Without this knowledge errors are frequently made, result¬ 
ing in some cases, in stones cracking and splitting, before the 
buildings in which they were placed were finished. In other 
cases the material, though specially selected for strength, 
gives way in the course of a few years, causing sometimes the 
complete destruction of buildings and even loss of life. 

If such knowledge had been accessible at the time of 
the erection of the Government Buildings at Washington, 
it is unreasonable to suppose that the Acquia creek sand¬ 
stones would have been selected; one of the very poorest 
of all varieties of that material, and of which the building 
commissioners of the Smithsonian Institution say, they 
would not have accepted it if it could have been placed 
upon their ground free of cost. 

Nor is it probable if this subject had received proper 
attention, that the Alum limestone would have been 
used in the Washington National Monument, a material 
so ill suited to the purpose, that Professor R. Johnson 
remarks, “ that it is not at all improbable that it will fall 
to pieces of its own weight before it is completed. 


30 


NOTES ON BUILDING STONES. 


In Europe, experiments of the kind mentioned, have 
been largely made, both for private purposes and for 
different governments. In the United States, researches 
of this and similar kinds have been made in hut a com¬ 
paratively few cases. Chief among them are those of 
Professors Henry and Johnson, Dr. Page' and Mr. Mills, 
whose papers have been largely used in preparing this 
statement. 

In this connection attention may he directed to the 
following tables, as containing matter worthy of careful 
consideration : 

Table III. Resistance to compression of stones used in 
certain ancient buildings. 

O 

Table IV. Resistance to compression of various building 
stones. 


TABLE III. 

Resistance to Compression of Slones used in Certain Ancient 

Buildings. 


EY M. RONDELET. 


Varieties of Stone. 


Caserti stone of Italy,. 

Stone of Istria, used in Venice and Vicenze,. 

Forneaux stone, pillars of All Saints church, 

Angers,. 

Grey stone, Florence,. 

Stone of bridge of St. Maurence,. 

Travertine, material of ancient Roman buildings,. 
Bayne.aux stone, Columns of Pantheon, Paris, 
Stone of Temple of P;estmn,. 


Area of base of speci¬ 
mens in sq. inches. 

Pressure per sq. inch 
required to crush, in 
pounds. 

2 

8,584 

2 

7,305 

2 

6,317 


6,006 


5,504 


4,301 


3,484 


3,358 



363 


316 


270 

261 

221 

183 

140 

136 



























TABLE IV. Resistance of Compression of Various Building Stones. 


NOTES ON BUILDING STONES 


31 


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32 


NOTES ON BUILDING STONES. 


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NOTES ON BUILDING STONES 


33 


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TABLE IV. Resistance to Compression of Various Building Stones — continued. 


34 


NOTES ON BUILDING STONES 


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NOTES ON BUILDING STONES. 


35 


The power of resistance to compression of different sized 
cubes of the same material varies much. It would seem 
to he probable, as Prof. Johnson has shown, that “ there is 
a direct relation between the power of the resistance of the 
cube, and the product of the area of the base, multiplied 
into the cube root of the area.” 

In those granites marked *, the experimental results are 
given in the figures enclosed in brackets, the probable 
results, if cubes of two inches were used are stated in 
the fourth column. 


d. Resistance to Frost. 

The effect of freezing and thawing in gradually disinte¬ 
grating stone, has already been mentioned, and it is plain 
that the comparative value of stones depends largely upon 
the degree of their resistance to these influences. As ordi¬ 
narily too much time would be taken by submitting them 
to the frosts of numerous winters, experiments have been 
devised to imitate this operation of nature, hastening the 
effect by increasing the energy of the action. 

1. Brard's method —To test the comparative durability 
of stone as affected by freezing and thawing, M. Brard 
proposed the following method, which was afterwards 
adopted by the engineers of bridges and highways in 
France, and was supposed to represent the action of frost. 

The specimens to be tested, cut into cubes, are satu¬ 
rated with a solution of sulphate of soda, and then sus¬ 
pended over cups. In drying, the salt forms crystals over 
the surface of the stone; these are washed off with the 
solution several times a day, for five days, into the cup 
beneath. If the stone is capable of resisting the action 
of frost, the crystals during their formation will detach 
nothing from it. If otherwise, small particles will drop 
off into the cup, and these being collected and weighed 


36 


NOTES ON BUILDING STONES. 


will give the .relative character as to durability of each 
specimen. 

Though experiments of this kind made in France, agreed 
with the .effects noticed by long continued exposure of the 
same stones in buildings, the report on stones for the 
new Houses of Parliament presents many instances of an 
opposite character. 

Prof. Henry says, though this process has been much 
relied upon and generally employed, the experiments 
made by Dr. Owen, lead us to doubt its perfect analogy 
with the operations of nature, the effects produced partak¬ 
ing of a chemical as well as of a mechanical action. 

Table V. shows the results obtained by Dr. Page with 
various stones treated by Brard's process. 


TABLE V. 


Jlesuli of experiments on Building Stones by Brard’s process to 
determine the comparcdive disintegrating effect of Frost upon 
them. The specimens used were one inch cubes. 

BY DR. CHARLES G. PAGE. 


1 

2 

3 

4 

5 

6 

7 

8 
9 

10 

11 

12 


Variety of Stone. 

Symington marble, close grained,. 

Pennsylvania blue limestone,. 

Symington blue limestone, . 

Pennsylvania marble, close grained,. ... 

Granite from Potomac Falls,. 

Symington large crystal marble,. 

Trinity church sandstone, close grained, N. J., 
Dark red sandstone, similar to Smithsonian,.. 
Coarse large crystal marble, Mt. Pleasant, 

N. Y.,. 

Hard brick,. 

Trinity sandstone, fine,. 

Light Seneca sandstone, dove colored,. 


Specific 

gravity 

2.834 

Loss during 
treatment 
in grains. 

0.19 

2.G99 

0.28 

2.613 

0.34 

2.727 

0.35 


0.35 

2.8G7 

0.50 

2.482 

0.62 

2.672 

0.70 

2.860 

0.91 

2.294 

1.07 


1.58 

2.456 

1.78 












NOTES ON BUILDING STONES. 


37 


Variety of Stone. 


15 Dark coarse sandstone, Peter’s quarry,. 

16 Connecticut sandstone, coarse grained,.. ... 


Specific 

gravity 

Loss during 
treatment 
in grains. 

2.518 

2.16 

2.607 

5.05 


5.60 


14.36 

2.211 

16.46 

2.230 

18.60 

2.583 

24.93 


% Actual freezing and thawing. Under the direction of 
Prof. Ilenry, experiments were made by submitting speci¬ 
mens to the action of a freezing mixture, sometimes for 
a period of twenty-four hours, at other times for twelve 
hours. The amount of exfoliation produced by the freez¬ 
ing was so slight, that the experiment had to be repeated 
many times before reliable comparative results could be 
obtained. 

The stone selected for the Capitol at Washington, was 
thus treated fifty (50) times, an inch cube losing only 
00.315 parts of an ounce, from which it was calculated 
that the freezing to which it would be subjected from 
natural operations, would produce exfoliation to the depth 
of an inch only after ten thousand years. 

Experiments made in this manner are troublesome, but 
would seem to offer more reliable results than can be 
obtained by any other method. 

Ho full report of the series of experiments referred to 
above, has ever been published, nor can it now be done, 
owing to the fact, that all of Prof. Henry’s papers on this 
subject were unfortunately destroyed in the fire.at the 
Smithsonian Institution in 1865. 







88 


NOTES ON BUILDING STONES. 


e. Resistance to Water containing Carbonic and other Acids. 

In this connection it may be mentioned that experiments 
made by acting upon building stones with water contain¬ 
ing carbonic acid might not unlikely assist in determining 
the relative durability of building stones, especially of 
those containing carbonate of lime and carbonate of 
magnesia. This solvent being everywhere present and 
always exerting more or less influence. 

So also the determination of the effect of sulphurous 
acid in solution in water, as well as others, might be 
useful as simulating the conditions found in many places. 
As has already been stated, the rapid destruction of the 
magnesian limestones of the British Parliament Houses, 
and the softer limestones sometimes used in London, are 
probably owing to the sulphur acids found in the smoke 
of that city. 


/• Porosity and Specific Gravity. 

The determination of the quantity of water that may be 
absorbed by a stone is important; for as Prof. Henry says 
it may be regarded as a measure of the antagonistic force 
to cohesion, which tends in the expansion of freezing to 
disintegrate the surface. 

The specific gravity oi the stone should likewise be deter¬ 
mined. 


<h Chemical Analysis. 

The chemical analysis of building stones is also import¬ 
ant, as frequently furnishing indications of value. It 
shows not only their general composition, but by it we are 
enabled to detect the presence of foreign ingredients, and 
determine the proportions in which they occur, and the 


NOTES ON BUILDING STONES. 


89 


effect they are likely to produce. The foreign ingredients 
oftentimes render a stone unfit for architectural purposes 
as has already been shown. 

The following points are worthy of attention, they par¬ 
take somewhat of the character of what has been stated, 
hut their importance entitles them to separate considera¬ 
tion. 


h. Ease of Working as affecting Cost. 

The ease with which a marble or other stone may be 
worked, does not depend upon its strength, but largely 
upon its hardness and upon the occurence of foreign 
minerals. 

Hence it is, that one marble, for example, at a less cost 
per cubic foot, will frequently because of the greater cost 
of working, from hardness, etc., cost more when laid in 
the wall, than another marble whose original price was 
greater. 


i. Variations in the Stone from the same Quarry. 

Quarries especially of the marbles, often vary much in 
the quality of the stone found in different parts or at 
different depths. A quarry which produces fine specimens, 
may be unable to furnish large quantities of as excellent 
material. 

Thus while some blocks in the State House at Albany 
are firm and free from flaws, most of them contain streaks 
and masses of mica, disfiguring the surface and diminish¬ 
ing the durability of the stone. 

Checks and flaws may occur frequently in the stone of 
of a quarry, even when the material appears sound, there¬ 
fore careful discrimination and actual working are required 
to determine its true value for architectual purposes. 


40 


NOTES ON BUILDING STONES. 


j. Capacity of a Quarry. 

The capacity of a quarry to produce a given amount of 
a certain quality of stone, in a given time, depends not 
alone upon the abundance of the material, but also upon 
the readiness with which it may be raised. 

Thus while a sheet of marble may extend an indefinite 
distance, the time and labor required to remove the super¬ 
incumbent earth, or the presence of water, may render 
the greater part practically unavailable. 

Furthermore while a quarry may be able to yield a large 
quantity of small blocks, it may be impossible to obtain 
from it large masses for columns, etc. 


fo, Cements and Mortars. 

The subject of cements and mortars is one deserving of 
far more care and attention than is usually bestowed 
upon it in this country. 

Many of the remarks made of building stones will apply 
to these materials, especially those regarding “ general 
chemical composition” and foreign ingredients.” 

Careful and repeated examinations ought to be made 
of them during the erection of important public buildings, 
to insure as well against neglect and ignorance as against 
the designed substitution of inferior materials. 

While the errors resulting from an improper selection 
of building stones, often become so apparent as to immedi¬ 
ately attract attention. Those arising from the use of poor 
mortars and cements, may not arise so early nor be so 
plainly manifested, frequently only gaining consideration, 
when serious danger is imminent. 


NOTES ON BUILDING STONES. 


41 


We h ave thus briefly considered the general character 
of building stones, the chief causes which affect their dete¬ 
rioration when applied to architectural purposes, and have 
mentioned the manner of determining their strength and 
durability. The illustrations that have been given show 
where the chances of error lie, and the serious mistakes 
that have been occasionally made in the selection of proper 
materials. 

They show that in this country selections of stone are 
generally made, even for important public buildings on 
incomplete information, and that, when more could readily 
be obtained. In other words, that large expenditures of 
money are made, without taking the precaution of remov¬ 
ing avoidable risks. 

It is not unreasonable to suppose that in a large majority 
of cases, the thorough examination of the building mate¬ 
rials would render unnecessary the occurrence of such 
expensive accidents as we have mentioned. It is certainly 
proper to say, with such examples before it, that the 
present generation owe it to those which are to follow, 
the use of all that skill and knowledge which the progress 
of chemical and mechanical science has endowed it, that 
posterity may have from us, something more substantial 
than the ruins we have inherited from the past. 


6 






REPORT 


BUILDING STONES. 

' BY 

PROF. JAMES HALL. 





REPORT 


ON 


BUILDING STONES. 



PROF. JAMES HALL. 


ALBANY, N. Y.: 

J. MUNSELL, 82 STATE STREET. 

1868. 







PRELIMINARY REPORT. 


Hon. Hamilton Harris, 

Chairman of New Capitol Commissioners. 

Hear Sir : According to instructions received from your¬ 
self and Hon. J. V. L. Pruyn in June 1867,1 proceeded to 
examine-the quarries of building stone within the limits of 
the State of Hew-York, and also those in adjacent States 
from which materials had been, or were proposed to be 
offered for the building of the new Capitol. 

To this object I devoted the greater part of my time 
during the remainder of the season, returning from my 
last journey on the 4th of December; leaving the investi¬ 
gation, however, very far from being completed. During 
this time I visited many of the quarries within the State of 
Hew-York and others in the State of Massachusetts, and 
some in Connecticut, Vermont, Hew-Hampshire, Maine, 
and Ohio. 

In order to have before you the tangible results of this 
investigation, I have brought to Albany, and deposited in 
the Geological Rooms, specimens from the greater part of 
the quarries examined. In nearly all cases the specimens 
were freely contributed by the proprietors of the quarries, 
and some of them in the most liberal and handsome man¬ 
ner, as I shall have occasion to mention in the course of my 



4 


Report on Building Stones. 


report. Other specimens have likewise been promised for 
the collection, from quarries examined, and from others not 
visited. The materials now arranged in the Hall of the 
Geological Rooms, though far from complete, constitute a 
valuable and instructive series of building-stones; from 
among which, I believe, satisfactory selections may be 
made, not only for the construction of the New Capitol, in 
its foundations and superstructure, but they will serve as 
a guide for architects and others in the selection of mate¬ 
rials for other purposes. 

I had hoped to be able to finish my observations upon 
the quarries, and the general distribution of building ma¬ 
terial, during the present season ; but other duties have 
prevented this, and I would respectfully suggest that some 
farther examination, particularly in some parts of New- 
York, be authorized by the Commissioners before the Re¬ 
port shall be considered complete. I venture to*suggest 
this, believing that a more acceptable service could not be 
rendered to the building and economic interests of the 
State ; and the New Capitol Commissioners have an oppor¬ 
tunity of rendering this service to the general welfare of 
the community, while fortifying themselves with all avail¬ 
able information to govern their own action in the selection 
of materials, not only for the exterior walls, but for interior 
use and decoration. 

For the latter object, I w r ould very earnestly recommend 
that specimens from all formations yielding marble, or of 
limestone bearing a good polish, be used in some part of 
the New Capitol w r ork. With this object in view, I have 
already procured specimens of some of these stones, but 
the collection in this department is scarcely begun. 

I have already recommended to you certain localities 
from which foundation-stones may be obtained. In this 
statement, I think I omitted, or did not definitely specify, 
the locality of Gneiss or Granite in the Highlands on the 


Report on Building Stones. 5 

Hudson river, of which the quarries at Breakneck and 
Butter hill offer good examples. 

As a preliminary to our inquiries after proper building- 
stone , we may first consider what are the materials with 
which we have to deal. The rocks or varieties of rocks 
offered in nature, and from which we are compelled to 
make our selections, may be named under the following 
heads: 

1. Granites, including Sienite, Gneiss, etc. 

2. Marbles, or Metamorphic crystalline limestones. 

3. Limestones, not metamorphic , compact or subcrystalline. 

4. Sandstones or Freestones, and their varieties resultiog from 

admixture of clay or carbonate of lime, etc. 

In the first place, it should he understood that under 
each of these heads there is an almost infinite variety in 
texture , color , power of resistance to pressure , durability , etc.; 
that the substances named are very widely distributed, and 
that they vary in different and distant localities; that a 
sandstone is rarely a purely siliceous rock, or a limestone a 
purely calcareous or calcareo-magnesian rock: other ma¬ 
terials foreign to their strict constitution, according to the 
usual designation, enter into their composition, and, for 
the most part, to the injury of the mass. In the purely 
sedimentary rocks, which have undergone no subsequent 
change, the sandstones are more or less permeated by 
argillaceous matter or clay, which constituted a part of the 
original sediment, and which may be uniformly mingled 
throughout the entire mass, or may form thin layers or 
seams separating the harder layers. In either case it is a 
dangerous ingredient; for no rock with clay seams can 
long be exposed to the weather, without a greater or less 
degree of separation or disintegration ; and when any con¬ 
siderable amount of the same material is distributed through 


6 


Report on Building Stones. 


t 


the mass, its ready absorption of water renders it equally 
dangerous to the stability and integrity of the whole. 
Placed beneath the surface, and beyond the reach of frosts, 
the conditions are different, and such rocks last for an in¬ 
definite period of time. 

The same remarks hold true with regard to limestones; 
and there are few limestones that are not marked by part¬ 
ings of shale or clay, which, in the course of time, weather 
into open seams, causing those unsightly appearances so 
common in structures of this kind. 

In the granite and crystalline limestones, other causes, 
as the want of cohesion among the particles, presence of 
destructive agents or liability to chemical changes, and 
seams or patches of foreign matter, are symptoms to be 
guarded against. It is not because a rock offered as a 
building stone is a granite , a marble , a limestone or a sand¬ 
stone , that it is good or bad ; but this characteristic is to be 
sought in other conditions, and the objectionable feature 
may be accidental or adventitious. 

One other condition should be remembered. These ma¬ 
terials used for building are not promiscuously distributed 
over the country, but are restricted to certain oreoWical 
formations, and can only be found within certain limits. 
Although we find granite, gneiss, and various sienites, 
with crystalline limestone, in the mountainous regions of 
Hoi them Hew-York, it would be quite absurd to look for 
rocks of this kind in the Catskill mountains. We find 
white and variegated marbles in the region skirting the 
Highlands on the east, and extending through Western 
Connecticut, Massachusetts and Vermont; but no well 
informed person expects this material in the Helderberg 
mountains, or in the hills of the southern counties of Hew- 
York. Investigation has shown that certain kinds of rock, 
01 locks of similar but very distinct characteristics, are con¬ 
fined to certain geological formations, and do not occur out 



Report on Building Stones. 


7 


of these; and, again, that these formations have certain 
limits which are already defined and well understood. 
Geology has so well defined these matters, and the associ¬ 
ation of certain rocks and minerals, that when told that a 
known geological formation covers a portion of country, 
we know what kind and character of rocks and other 
mineral products to expect. 

In a State where the geological structure is so well known 
as that of Hew-York, I think I may he allowed to speak of 
the various building materials under the heads of the several 
geological formations to which they belong, or in which 
they occur; thus conveying general information, while 
treating of the special subject . 

All the Granites, granitic , sienitic , or gneissoid rocks of 
the State are confined either to the northern portion, known 
as the Adirondac region, from the name of the high moun¬ 
tain range in its central part; or, to the Highland region 
along the Hudson river, which is of the same geological 
age as the northern portion, and all belonging to the Lau- 
rentian System. 

In the northern part of the State, Crystalline limestone, 
of various colors, is associated with granitic or gneissoid 
rocks: the same is true, in a less degree, of the granitic 
region of the Highlands. 

The White and Variegated marbles, so much in general 
use, belong to a different geological age and constitute a 
distinct belt of formation, running to the eastward of the 
highlands generally, and occupying portions of Westchester 
and Dutchess counties in Hew-York, and thence extending 
into Connecticut and Massachusetts. The ordinary gray 
or dark-colored bluish limestones and the various colored 
sandstones have a much wider distribution, hut are still 
limited to certain belts of country. 

Treating these in their order, we may arrange and dis¬ 
cuss them as follows : 



8 


Report on Building Stones. 


I. Granites, including Sienites, Gneiss, or gneissoid 

AND SIENITIC ROCKS ; THEIR GEOLOGICAL POSITION AND 

GEOGRAPHICAL DISTRIBUTION. 

The term granite, in its strict signification, means a crys¬ 
talline rock composed of quartz, felspar and mica in inti¬ 
mate mixture, the separate minerals being composed of 
crystalline grains. It is a very common condition of the 
granitic rocks, that the mica may be absent, and in its stead 
we have hornblende; and in this form the rock is termed 
a sienite.* On the other hand, the presence of mica in 
thin scales, forming lamination, or rendering the lines of 
bedding visible by coloration or otherwise, produces what 
we term gneiss; though some geologists would apply the 
term gneiss to all stratified granitic rocks. 

The proportion of mica in gneiss is not necessarily larger 
than in some of the granites; but the faces of the thin 
laminae being arranged parallel to the lines of bedding and 
the freest line of cleavage, causes it often to appear in 
larger proportion.f 

Quartz, felspar and hornblende without mica or with a 
very small proportion of this mineral, constitute some of 
the best granites; while in the lighter gray or whitish 
gray granites, the quartz or quartz and felspar are the 
chief component parts, and there is little either of horn¬ 
blende or mica. The grains or aggregations of these mi¬ 
nerals may sometimes be so large that each one presents its 
distinctive mineralogical or individual character, becoming 
so coarsely crystalline as to be unfit for building purposes. 

* The Egyptian sienite or syenite, according to Delesse, contains mica. 

t A distinction has sometimes been made between gneiss and granite, that 
the one is stratified and the other not. This does not hold true ; for nearly 
all, if not all, the granites that are extensively quarried are stratified, and I 
- believe all of them cleave in one direction more freely than in another, while 
the other free line of cleavage or breaking is rectangular to the first. 



Report on Building Stones. 


9 


Granites of New-York. 

In the lower portion of the Adirondac region, or the 
Laurentian System bordering Lake Champlain and ex¬ 
tending from Saratoga to Clinton county, the rocks con¬ 
sist mainly of a gray gneissoid granite, which is sometimes 
traversed by coarser crystalline veins, and sometimes 
nearly or entirely losing its gneissoid character from the 
small proportion of mica, but always regularly stratified. 
The latter character is presented in the exposures at 
Littlefalls and other places ; while the true compact gneiss 
is seen at the quarries in Saratoga county, and the partial 
or entire absence of the mica characterises the rock at 
many localities farther to the north. This gray gneissoid 
rock graduates downwards, through alternating beds of 
variable character, into a hornblende rock, and becomes a 
compact dark-colored sienite extremely hard and tough in 
its character. 

The same general features prevail in the granite rocks 
in the Highlands as exposed along the Hudson river, the 
strata being tilted at a high angle. In many places, 
however, the lines of bedding become obscure, the mica is 
in a great degree absent, and the rock assumes the cha¬ 
racter of a true granite. The principal points of exposure, 
where the gneiss or granite of the Highlands has been 
quarried, are at Butter hill on the west side of the river, 
and at Breakneck on the east side. In some portions of 
the mass, at both of these localities, the rock loses in a 
measure its gneissoid character, and presents a compara¬ 
tively even admixture of the component parts. At both 
localities the rock is penetrated by trap dykes, which have 
affected the beds adjacent to them; and these, together 
with other causes, have produced a more than ordinarily 
fractured or jointed condition of the rock. 

2 


10 


Report on Building Stones. 


In the higher part of the Laurentian series, and in 
localities more inaccessible to means of transportation, 
we have the highly felspathic granites of the central 
portion of the Adirondac region. These are usually 
coarsely crystalline and of a dark color, but weathering to 
a lighter hue. They have nowhere been brought into use 
for building purposes ; and not being within the limits of 
reasonable cost of transportation, it is scarcely worth while 
to indicate their localities more particularly. 


2. Granites of New England. 

The granites examined beyond the limits of the State, 
belong to an entirely different geological age from those 
of New York, and present a different aspect in the aggre¬ 
gation of their component parts. They moreover differ 
among themselves, in a very extreme degree, both in 
color and texture ; varying from the dark-colored compact 
sienite of Quincy and the neighborhood, through the lighter- 
colored varieties of the same locality and that of Chelms¬ 
ford and other places, to the greyish white varieties like 
that of Rockport on Cape Ann. All the quarries that I 
have examined along the coast are free from mica; and 
when hornblende is not present, we have the quartz and 
felspar only. The dark colors are usually due to the 
presence of hornblende ; the reddish or brownish colors, 
to the colored felspar; and some of the quarries offer a 
granite of quartz, brownish felspar and dark hornblende, 
giving thus within these ranges a considerable variety of 
color, due either to the original color of the substances, or 
to the proportions in which they are mingled in the mass. 

The principal quarries that came under my observation 
were those of Quincy and Weymouth, Rockport on Cape 
Ann and Dix island in Maine, with others of less import¬ 
ance. The collection embraces specimens from each of 


Report on Building Stones. 


11 


these places. All of the granites (sienites) quarried along 
the coast are durable stones ; a character determined as 
well from their abundant use in building, as also from 
their exposed surfaces in nature, which have withstood 
the action of weathering for centuries without perceptible 
disintegration. 

The granites of the interior of Hew-England, as of 
Concord and Fitzwilliam in Hew-Hampshire, Hallowell 
in Maine, Medfield in Massachusetts, Westerly in Rhode- 
Island, and of Barre, Berlin and other places in Vermont, 
are compounds of quartz, felspar and mica. They are, 
for the most part, light colored and fine grained. The 
felspar predominates, and they are easily wrought and 
hear fine working. 

The Concord granite, which is now so largely in use, oc¬ 
cupies a long hill near the town of Concord in Hew-Hamp- 
shire, which has a direction or range from northeast to 
southwest. It is quarried at several places on this hill, within * 
a moderate distance from the town and railroad. The rock 
presents distinct lines of bedding with an apparent dip to 
the northwest, as indicated by seams or laminae of different 
color, and also by the splitting of the rock both in the line 
of rift (so termed by the workmen), and in the direction 
perpendicular or vertical to the lines of bedding.* 

The beds of this granite are unequal in thickness, vary¬ 
ing from one to three or four, or even five or six feet, 
which can he split in any desired lengths. The texture is 
pretty even, with some coarser beds, with occasionally 
some blotches of coarser or finer, or lighter or darker 
material. 

The granite of Fitzwilliam, a locality some forty miles 
west of Concord, occupies a hill having a direction from 

* In splitting tlie blocks vertically to the bedding, I am informed by the 
foreman of the quarry, Mr. Rob, that they open much more readily in lines 
east and west and north and south, than in any direction oblique to these. 



12 


Keport on Building Stones. 


northeast to southwest, with the dip apparently to the 
northeast. In texture and quality it is very similar to 
that of Concord; the prevailing beds perhaps a little 
thinner, the thickest being four feet. The rock is easily 
worked, and can be dressed with great facility.* 

A mile northward of the principal quarries the rock is 
somewhat coarser in texture, but of similar light gray 
color, readily worked, and making a handsome building # 
stone. The granite of Hallowell in Maine is similar in 
texture to that of Concord and Fitzwilliam. 

There is also a light-colored granite in the town of 
Medfield in Massachusetts, from which the Court-house 
in Dedham has been built. In color and texture, this 
granite differs but little from the Concord granite, being 
perhaps a little coarser. The Court-house was erected 
more than forty years ago; and considering the time and 
the less perfect dressing of the stone as compared with 
work of the present day, the building still presents a 
very fine appearance. 

The granites of Barre, Berlin and other places in Ver¬ 
mont, are of a whitish gray color, with the component 
parts very distinctly granular and evenly mixed through¬ 
out, containing less mica than the Concord and Fitzwilliam 
granites, and producing one of the finest building mate¬ 
rials in the country ; possessing a fine color, strength and 
durability. 

II. Marbles, or Metamorphic Crystalline limestones; 

THEIR GEOLOGICAL POSITION AND GEOGRAPHICAL DISTRIBU¬ 
TION. 

Crystalline limestones are everywhere interstratified 
with the gneiss rocks of the Laurentian System, but usu- 

* I am informed that the statues on the Horticultural Hall in Tremont- 
street, Boston, are from the Fitzwilliam granite, the structure itself beimr of 
Concord granite. 



Keport on Building Stones. 


13 


ally forming a very small proportion of the entire mass. 
These limestones frequently contain a large proportion of 
other minerals, as serpentine, augite, etc.; often pro¬ 
ducing a marble of variegated character which is quite 
ornamental. When free from these materials, it is often 
grayish or bluish gray, and generally coarsely crystalline. 

Limestones of this age follow the line of outcrop of the 
gneiss of the same system ; appearing to the northward in 
Saratoga county, and extending thence with more or less 
continuity through Warren, Essex and Clinton counties. 
In St. Lawrence and Jefferson counties, the crystalline 
limestones of the same age are more extensively developed, 
and have there been known and used for a long time. The 
same limestones likewise occur in Lewis county. In some 
localities these limestones are cut and wrought as a marble ; 
but generally they have only a local use, though some of 
them with the serpentine admixture may yet prove of 
general commercial value. 

The white and variegated marbles of commerce are 
mainly confined to the geological formation known as the 
Quebec group, which underlies a belt of country extending 
from Canada through Vermont, the western part of Massa¬ 
chusetts and Connecticut; thence into the eastern part 
of New-York, through New-Jersey, Pennsylvania, Mary¬ 
land, etc. 

The marbles of this group are largely quarried in West¬ 
chester county; and the quarries of Tuckahoe and Sears- 
dale, and other points, furnish large quantities of the 
material for buildings in New-York city and elsewhere. 
The rock is rather coarsely crystalline, but compact and 
durable. The same marble, on the west side of the syn¬ 
clinal axis, is quarried at Hastings and at Singsing, and 
also at several places in Dutchess county. 

The formation is abundantly developed in Litchfield 
county in Connecticut, and at Stockbridge, Sheffield, 


14 Report on Building Stones. 

Egremount, Barrington, Alford and other places in Mas¬ 
sachusetts. 

In its northern extension, the same formation furnishes 
the marbles of Vermont, at Rutland, Sutherland falls, 
Brandon and other places. 

Neither to the eastward nor to the westward of this form¬ 
ation are there any extensive beds of white or variegated 
marble, and the great sources of this material for building 
and ornamental purposes is to be sought in this range of 
rocks. 

III. Limestones not metamorphic, compact or subcrys¬ 
talline ; THEIR GEOLOGICAL AND GEOGRAPHICAL DISTRI¬ 
BUTION. 

The limestones used in building, or for foundations, 
canal locks, bridge abutments and other solid masonry, 
are very widely distributed, and in great variety within the 
State of New-York. 

In their geological order, we have the Chazy limestone , the 
Ti'enton limestone group (embracing the Birdseye , Black-river 
and Trenton limestone proper), the Niagara limestone , the Lower 
and Upper Helderberg limestone groups , and the Tally limestone. 

These limestones vary from a dark bluish-black or black 
color to bluish gray, gray, or sometimes reddish or brownish 
gray. 

1. The oldest of these, the Chazy limestone, as its name 
indicates, occurs at Chazy in New-York. It forms the 
island known as Isle la Motte, and other islands in Lake 
Champlain, and extends likewise into Vermont and Ca¬ 
nada. It exists in heavy beds, and is largely quarried for 
different purposes, as will be mentioned hereafter. 

2. The Trenton limestone group, in one or more of its 
members, occurs both on the east and west shores of Lake 
Champlain, and is extensively quarried at Wilks'borough 
and other places. The same rock occurs at Giensfalls 


Report on Building Stones. 


15 


and in the neighborhood of Saratoga-springs. It likewise 
extends along the Mohawk valley from the neighborhood 
of Hoffman’s ferry to Littlefalls, and is quarried at Am¬ 
sterdam, Tribes-hill, and other places. At Littlefalls the 
continuity of the limestone formation is interrupted by 
the southern extension of the Gneiss formation, but it 
comes in again to the south and west beyond this, and is 
extensively quarried at Jacksonburgh on the south side of 
the Mohawk river. The same formation extends, by the 
way of Trenton falls, through Lewis and Jefferson counties, 
everywhere offering quarries for building-stone and for 
lime. 

3. The Niagara limestone, though extending farther to 
the eastward, acquires little force or thickness till we reach 
Monroe county, where it has a considerable thickness on 
the Genesee river, and some of the beds of the formation 
are valuable as quarry-stones. It is only in the neighbor¬ 
hood of Lockport, however, that the lower beds of this 
formation become important as a building stone. The 
principal working beds are a light gray stone, varying in 
some instances to a brownish color from the admixture of 
organic remains. The same limestone occurs at Niagara 
falls and vicinity, extending thence through Canada West 
to Lake Huron. The upper parts of the formation are of 
a brownish, or often of an ashen gray color, with irregular 
bedding and of unequal texture, as well as marked by ca¬ 
vities and crystalline masses of calc-spar, selenite or com¬ 
pact gypsum, celestine, etc. The stone of this part of the 
formation is adapted only to the heavier and coarser ma¬ 
sonry, and care is required in its selection to secure a strong 
and durable stone. 

4. The Lower Helderberg limestone formation, in its 
most easterly extension within New-York, appears in the 
Helderberg mountains and extends west as far as Herkimer 
county. The lower beds of the formation afford a very 


16 


Report on Building Stones. 


excellent building stone of a dark bluish color, which, 
when polished, is nearly black. It is principally quarried 
at Schoharie and Cobleskill: it is likewise worked at Carlisle 
and Cherry-valley, and to a small extent at points west of 
the latter place. The middle portion of the group consists 
of a gray or bluish gray subcrystalline limestone, but 
affords no beds of great value for building material. The 
upper member of this formation is a gray subcrystalline 
limestone, sometimes variegated with brownish spots from 
organic remains. It is quarried both for a building stone 
for rough masonry, and likewise for a marble, bearing a 
pretty good polish, and the variety of color from the fossils 
gives it a handsome appearance. 

5. The Upper IIelderberg limestone formation consists 
principally of two members, the Onondaga and Seneca 
limestones. The former was so named from its having 
been extensively quarried in Onondaga county; and the 
latter, from its greater development in Seneca county. 

This formation, or group, extends through the State of 
Hew-York from the Hudson river westward to Black-rock 
on the Niagara. Constituting the higher limestone of the 
IIelderberg mountains, it approaches the river, and con¬ 
tinues in its outcrop along the river counties as far as 
Kingston in Ulster, where one of its members is largely 
quarried for various building purposes. The Onondaga 
limestone is worked at various points along its outcrop; 
but the principal quarries are in the county of Onondaga, 
to the southward of Syracuse. From this neighborhood, 
the stone was used for building some of the locks on the 
Erie Canal in its original construction, and has been ex¬ 
tensively used in the enlarged canal, as well as in the 
buildings of Syracuse. The upper member of the forma¬ 
tion is quarried at Springport in Cayuga county, and 
largely in the neighborhood of Seneca falls. From this 
point through the western counties, one or both the mem- 


Report on Building Stones. 


17 


bers of this group are more or less extensively quarried, 
and used in building, or for door and window caps and 
sills, foundations, and other masonry. 

6. The Tully limestone constitutes a belt of formation 
of from one to twenty-five feet in thickness, lying above 
the shales of the Hamilton group and below the Genesee 
slate. The geographical extent of this formation is very 
limited, having no great thickness or importance to the 
east of Cayuga county, and almost entirely disappearing 
on the west within the limits of Ontario county. It is 
mentioned here among the sources of building material, 
but it is rarely in such a condition as to be reliable for 
this purpose. 

IV. Sandstones or Freestones, and their varieties ; 

THEIR GEOLOGICAL POSITION AND GEOGRAPHICAL DISTRI¬ 
BUTION within the State oe Yew-York. 

1. The Potsdam sandstone formation is the lowest 
member of the unaltered stratified rocks. The formation 
consists of numerous beds of varying thickness, and of a 
gray, white, buff or red color. The rock is naturally fine¬ 
grained and compact, and in many localities furnishes a 
strong durable material. The beds are usually thin, but 
generally sufficiently thick for the ordinary purposes of 
construction. 

In its eastern extension, this formation occupies a con¬ 
siderable area in Washington county, and is especially 
conspicuous in the neighborhood of Whitehall. It occurs 
at numerous places along the west side of Lake Cham¬ 
plain, and is especially developed in the neighborhood 
of Keeseville. In some parts of Clinton county, the rock 
is too friable for any economical use beyond furnishing 
sand for glass-making. In Franklin county, at Malone, 
the rock has been extensively quarried and used for 
building and flagging stones for many years past. At 


18 


Report on Building Stones. 


Potsdam and other places in St. Lawrence county, the 
stone is of a reddish brown color, close-grained and com¬ 
pact in texture. The rock continues of similar character 
in Jefferson county on the north side of the Black-river 
valley. Its commonly striped or variegated color offers 
an objectionable feature for general use in building. 

2. Sandstones and argillaceous sandstones of the 
Quebec and Hudson-river groups. Certain parts of both 
of these groups of rocks furnish building-stones of greater 
or less value. The greater part of the stone known as 
Blue stone (the Malden blue stone belongs to a different 
formation and has a different character), along the Hudson 
and Moffawk valleys, is derived from one or other of these 
formations. The higher beds of the Hudson-river group 
have also been quarried in Oneida, Oswego and Lewis 
counties, but they are not extensively used. 

The quarries along the Mohawk-river below Schenec¬ 
tady have furnished a large quantity of this blue stone, 
for foundations, water tables, and for entire buildings. 
Where the strata are but little disturbed and lie nearly 
horizontally, the beds are easily worked, and the blocks 
are readily dressed. The rock can be quarried in regular 
masses and of any required dimensions. In the valley of 
the Hudson, the rock is so much disturbed that the strata 
are broken, and do not readily afford the means of furnish¬ 
ing large quantities of regular formed blocks for masonry. 
Nevertheless they are largely used for foundation-stone, 
and many thousands of tons are annually quarried along 
the river. At and below Poughkeepsie, the stone of this 
character, quarried along the river, is of the Quebec 
group. The strata all consist of an argillaceous sandstone, 
very compact and strong, but breaking irregularly. Those 
which break into large masses are very strong, and 
make excellent foundation stones; but I believe none of 
the beds are used for dressed stone. 


Report on Building Stones. 


19 


The two formations lie side by side along the Hudson- 
river valley, extending northward through Washington 
county and into Vermont and Canada. 

To the westward, the Hudson-river group extends along 
the Mohawk valley, and thence in its upper members 
through Lewis and Oswego counties; overbearing in its 
upper part some heavy-bedded gray sandstone which is 
available for foundations and rough masonry, hut I am 
not aware that it has been much used in the superstruc¬ 
ture of buildings. 

3. The Medina sandstone formation, from its eastern 
extension in Oswego county to the Niagara river, fur¬ 
nishes building stone in some of its beds, which, in some 
localities is good and reliable, while in other parts of the 
same formation it becomes rapidly disintegrated upon 
exposure to the atmosphere. It is quarried at Fulton and 
other places in Oswego county, and at a few points in Wayne 
county. It has been heretofore quarried on the Genesee 
river below Rochester ; but the more reliable quarries are 
at Holly, Albion, Medina and Lockport; and again it crops 
out in the bank of the Niagara river above Lewiston, where 
it can be worked with facility. The formation furnishes 
valuable flag-stones in the neighborhood of Lockport. 

4. Sandstones of the Clinton group. The Clinton 
group is made up of a series of shales, thin beds of lime¬ 
stone, and impure shaly sandstone with more perfect beds 
of the latter. In Herkimer county, on the south side of 
the Mohawk river, there are some beds of brown sand¬ 
stone in this group which are worthy of attention. The 
material is mainly siliceous and the texture good. So far 
as known, these beds are limited within the width of the 
county. In the same neighborhood, and lying above the 
brown beds, there is a considerable thickness of gray 
siliceous sandstones of the most durable character. So 
far as known, the rock has not been quarried to any con- 


20 


Keport on Building Stones. 


siderable extent, and its economic value is therefore not 
fully known. In other parts of the Clinton group, there 
are thin flaggy beds which are used for rough building or 
foundation stones. 

5. The Oriskany sandstone, though a good and valu¬ 
able stone in some of its strata, does not occur in such 
thick or extensive beds as to render its use very extensive, 
and, except localty, it is unknown as a building stone. 

6. Freestones or Argillaceous sandstone and flag¬ 
stone of the Portage group and upper part of the 
Hamilton group. In Eastern Hew-York, the upper part 
of the Hamilton group and lower part of the Portage 
group yield an abundance of the finest flagstone yet 
known in any part of the country. Some of these beds 
become thick enough for building purposes; and the fine 
“ Blue stoiie ” of the Malden quarries on the Hudson river 
(now much used), is from the lower part of the Portage 
group. In Central Hew-York, the upper part of the Port¬ 
age group yields an abundance of fine-grained argillaceous 
sandstone, which is not always durable. In the extreme 
western counties of the State, however, some of the beds 
are durable, and make a valuable building-stone. 

The extension of the same formation into Ohio yields the 
famous fine-grained sandstone of Berea, and the gray free¬ 
stone of Amherst and vicinity; the latter of which is now 
so largely used for building in Hew-York and Philadelphia, 
Cleveland mid Buffalo, and which enters into the construc¬ 
tion of the Houses of Parliament at Ottawa. 

This sandstone, like all others of the same class of rocks, 
is very variable in its character at different points along 
the outcrop of the formation; owing chiefly to the greater or 
less proportion of argillaceous matter contained in the mass, 
and sometimes the almost entire absence of that material. 
The latter condition exists in some of the beds at Berea, but 
more particularly in those of Amherst and neighborhood. 


Report on Building Stones. 


21 


7. The sandstone and Argillaceous sandstone of the 
Chemung group are very irregularly distributed over the 
southern countries of the State. The beds tit for building- 
stone are usually intercalated between shaly beds, and 
sometimes continuous for many miles; while the coarser 
masses are not infrequently lenticular in form, thinning 
away in every direction, or ending in thinly laminated 
beds which are unfit for building-stone, but may be used 
for flag-stones. 

The stone varies in different localities and in different 
beds, from fine sandy layers of a light gray color, to more 
or less of an argillaceous character with a dark olive-brown 
color. It is not possible to trace any set of beds continu¬ 
ously through the country, and the rock can scarcely come 
into general use for building purposes. In certain localities, 
the arenaceous beds will prove of great value to the imme¬ 
diate neighborhood. 

* 8. Hew Red sandstone. Within the State of Hew-York, 
this rock is limited to the county of Rockland; extending 
from Haverstraw along the river, beyond the limits of the 
State into Hew-Jersey. The same sandstone has a wide 
area in the Connecticut river valley, and it is from this 
region that we chiefly know it in its uses as a building- 
stone. Within the State, the stone has been quarried at 
Haverstraw, and on the river bank below; though it has 
not been extensively used from these localities, so far as I 
know. The quarries in Hew-Jersey have been more exten¬ 
sively worked ; and from the stone there obtained, some 
fine structures have been erected. The same formation 
extends through Maryland, where it has furnished mate¬ 
rial for the erection of the Smithsonian Institution and 
other buildings in Washington. 

The Brown stone , in its varieties, is well known in all the 
Atlantic cities, and has been more extensively used than 
any other in the country. 


22 


Report on Building Stones. 


I have here sketched, in a hasty manner, the general 
geological and geographical distribution of the principal 
building-stones which may be brought before you for con¬ 
sideration. The portions of country occupied by these have 
been roughly traced in different colors upon the map accom¬ 
panying this report, so far as it covers the ground. I shall 
hope to have an opportunity of completing this work, and 
presenting such a map as will illustrate the important points 
relating to the subject of materials for construction and 
ornamentation. 

Y. On the selection of Building-stones, and the causes 

OF THEIR DECAY. 

In the selection of building-stones for the exterior walls 
Color , of a building, color , texture , and durability are objects of the 

an? n J}£!r« i m P or t ance 5 a ^d a ^ °f these ought to be combined, 
biuty. to render the structure perfect. Too little attention has been 
given to the subject of building stones; and while on the 
one hand we are largely using a brown stone, which gives 
a sombre cheerless aspect to the structure, the opposite 
extreme has been sought in the white marble, or that 
which is more nearly white in color. In contrast with 
these, we have the red glaring color of brick; and it is 
only partially that this offensive aspect is palliated by 
painting of neutral tints. In a few eastern cities and 
towns we find the light gray granites now used in prefer¬ 
ence to the brown freestone, the white marble, or the 
dark granite which have been much in use in past years. 

Ro one can fail to experience the sensation of relief 
Li^ht-^ afforded by the structures, of light-colored granites in the 
granites, city of Boston, or those of the buff* or dove-colored lime¬ 
stone in the city of Chicago, or of the light gray freestone 
of many buildings in Cleveland and other places, and of 
the buff-colored brick of Milwaukie. In these cases we 
have not the excessive reflection of light, or the glare 


23 


Report on Building Stones. 

which comes from white buildings whether of marble or 
of painted brick ; nor the sombre cheerless expression of 
the darker stone, caused by its great absorption of light. 

It is only necessary to consider the effects produced by 
the structures of these different materials upon one’s own 
sensations, in order to determine what are the most agree¬ 
able tints, or those which please the eye and produce a 
cheerful impression upon the mind. 

In the majority of structures, the necessities of locality, 
cheapness, or other causes compel the erection of struc¬ 
tures from materials most accessible ; but these considera¬ 
tions are not imperative in the case of an important public 
building. 

In many cases where the rock is homogeneous through¬ 
out and the color uniform and satisfactory, it is only to influence 
be inquired whether the coloring material is such as willmatte?on 

A ° < the dura- 

produce decay or disintegration of the particles. When bilit yof 
the general color is produced by the aggregation of differ¬ 
ent materials of distinct coloration, the character of each 
one is to be considered, and its effect upon the whole ; and 
it is important to have such material comparatively fine¬ 
grained, and the different parts as uniformly mingled 
together as possible. As a general rule, it is only in the 
darker stones that the coloring matter has any tendency 
to disintegrate the mass. 

In the selection of building stones, the simple presenta¬ 
tion of a sample is not enough. The rock in place should a sample 
be examined in the outset; for in its natural outcrops it not reiia- 

ble. 

has been exposed to the action of the weather, in all its 
influences, for many thousands of years. One of the Evidences 
principles taught in elementary geology is that the soft ity in expo- 

x . . sures. 

and decomposing rocks appear in low rounded or flattened 
exposures, or entirely covered by the soil or their own 
debris, forming no conspicuous feature in the country; 
while on the contrary the harder rocks stand out in relief, 


24 


Report on Building Stones. 


Features producing marked and distinguishing features in the 
ducedby l an dscape. It not unfrequently happens that the geologist, 
formation, having familiarized himself with the succession and cha¬ 
racter of the rocks of a particular locality or neighbor¬ 
hood, by seizing the features and character of the prominent 
beds, is able to trace them in succession along the escarp¬ 
ment or mountain range as far as the eye can reach, and 
to approach them from any distant point with assurance 
that he has not been deceived. 

The strata which make these features in the land¬ 
scape are the ever-enduring rocks, which have withstood 
the action of the atmosphere through a period a thousand 
times longer than any structure of human origin. One 
cannot doubt that if properly placed in any artificial 
structure, they would still withstand the action of the 
Escarp- elements. These escarpments, in their natural situation, 
be coarse, may be coarse, rough and forbidding, more or less dilapi- 

rough and J 7 ° 07 r 

diug d but dated of unequal]} 7 dilapidated from the effects of time; but 
durable. ag ^hey there present themselves, we shall be able to 
see their future in any structure exposed to the same 
influences. 

It is true, however, that no artificial structure or position 
ciaipoB?- ever subject the stone to the same degree of weather- 
subjectthe influence to which it is exposed in its natural position, 

stone to 


BlUUli IU Till 1 • 1 • 1 1 

the degree but the same changes in degree will supervene upon any 
freshly exposed surfaces. In its natural position the bed 
has been encased in ice, washed by currents, saturated with 
rains and melting snows, frozen and thawed, and exposed 
to the extreme of summer heat without mitigation. The 


ering it 
has had in 
nature. 


% 

rock which has withstood these influences is quite equal to 
withstand the exposures of a few centuries in an artificial 
structure. Yet there are occasionally modifying influences 
and conditions which have sometimes subdued the perma¬ 
nence of a durable stone, and given preference to others 
less durable. It therefore becomes necessary to carefully 


Report on Building Stones. 


25 


» 

examine all these conditions, and to determine not only 
from the rock in place, but also from its physical consti¬ 
tution, whether it will meet the requirements of the 
structures proposed. 

It not unfrequently happens, in working a quarry, that 
layers are reached which have not been exposed to the 
weather, and it is then necessary to test the strength and 
power of endurance of the stone. This may be done by 
repeated exposure to freezing and thawing, by testing the Artificial 

freezing 

strength or power of resistance to pressure, etc. The ex- and thaw- 

. . . mg as a 

posure to freezing and thawing will not only determine its test - 
power of resisting the action of the weather, but will deter¬ 
mine also whether such foreign ingredients as iron pyrites 
• may exist in the mass. Chemical analysis may be resorted chemical 

.... composi- 

tO, for the purpose ot comparison with specimens of known tionaicmc 
composition and durability; but chemical analysis alone timinin^ 
cannot determine, without other testing experiments, the durablllty * 
strength or power of endurance of the stone. 

In some countries, and in certain localities in our own 
country, the evidence obtained from ancient structures is Evidence 
available in determining the durability of the stone which cientstruc- 
has been used. Yet it would seem that this information where 
has been of little avail in many places, where the rebuild- nabhT re " 
ing of edifices is repeated every century. Experience in 
many cases does not teach the lesson anticipated; and 
when a dilapidated structure is pointed out, the argument Tim plea 
is made that “these stone were not well selected,” or they specimens 
were obtained “at the first opening of the quarry, and were ^klvlr- 
not as good as now furnished.” And again, as already bffng°Sir- 
remarked, there are few cases in which parties are pe !l’- mens is 

fallacious. 

mitted to select the material without prejudice, the influ- Thedeeper 
ence of interest, or the absence of important information, 
Examples are everywhere before us of the improper selec- to assume 0 

r the same 

tion of materials for buildings, and these examples do not condition, 
deter from their use in the erection of others. When good 

4 


26 


Report on Building Stones. 


material is abundant and accessible, it will be used; in other 
situations, comparatively few durable structures are likely 

to be erected. 


YI. General composition and comparative durability 

OF BUILDING STONES. 

All the stones used in building, under whatever name 
they may be known, are composed of a few essential ele¬ 
mentary minerals; these are, 

1. Silica or Quartz; 

2. Alumina-Clay or Argillaceous matter; 

3. Carbonate of lime ; 

4. Carbonate of magnesia. 

Beyond these, except in crystalline rocks, the presence 
of other material is almost non-essential to the composition 
of the stone, often accidental or adventitious, and usually 
injurious to the integrity of the mass. The ultimate che¬ 
mical composition of a stone has little to do, as a general 
rule, with its character for durability ; nor will a chemical 
analysis determine the value of a 3tone for building pur¬ 
poses. 


Physical conditions of the aggregates of the several 

NAMED SUBSTANCES. 

1. The silica or quartz may occur as a mechanical aggre¬ 
gation of particles of sand simply cohering among them¬ 
selves, or by the intervention of some argillaceous, ferrugin¬ 
ous, or calcareous matter acting as a cement; or lastly 
through a partial solution and cementation of the siliceous 
particles themselves. In the latter case, and where the 
mass is pretty purely siliceous, the process may have gone so 


Report on Building Stones. 


27 


far as to give a vitreous rock known as quartzite. In many 
cases, however, the siliceous or arenaceous deposits present 
great inequalities of texture, from the aggregation of coarse 
particles or small pebbles among the finer materials, always 
to the injury of the strength and durability of the mass. 
Under certain other conditions, these mixtures become 
crystalline rocks of various character. 

2. The clay, or argillaceous matter by itself or with a 
small admixture of silica, and often more or less of carbo¬ 
nate of lime, becomes a slate or shale rock, but quite unfit 
for building stone ; and as a general rule, any rock in which 
argillaceous matter predominates is unfit for a durable 
building stone. 

3. Carbonate of lime and magnesia, or the former alone, 
constitutes extensive beds of solid and durable stone, but 
which is often deteriorated by the presence of argillaceous 
matter. In many limestones, the mass consists of an aggre¬ 
gation of fine particles which have been deposited in the 
form of a fine calcareous mud. Other and often very ex¬ 
tensive beds are visibly composed of the debris of shells 
and other organic bodies, cemented together by the finer 
particles of calcareous mud, or often by the partial solution 
of calcareous matter. Under the influence of subsequent 
conditions, these simple mechanical aggregations of calca¬ 
reous matter, or the calcareous magnesian deposits, become 
crystalline marbles of various colors. 

In the purely siliceous stones, or quartzites, the mass issand- 

ii* „ stones 

too hard and brittle for easy working or comely shaping ot 
the pieces ; an admixture of clay or argillaceous matter be¬ 
ing essential to the possibility of working stone whose basis 
is silica. When, however, this argillaceous material be¬ 
comes excessive, the stone is liable to rapid disintegration 
from the action of the weather. While the silica absorbs 
but an extremely small quantity of water, the clay will 
absorb largely; and this, on freezing, will destroy the stone 


28 


Report on Building Stones. 


more.or less rapidly. Some of the argillaceous sandstones, 
on drying in a hot sun and then being suddenly wetted, 
will crack and crumble into pieces. The same effect is 
often produced by the sudden freezing of large blocks 
which have been freshly quarried, and which still retain 
their water of absorption. 

When the argillaceous matter is evenly and intimately 
mingled with particles of silica or quartz, and not in too 
large proportions, the stone will last a long time, and will 
disintegrate but slowly; but when the argillaceous mate¬ 
rial is in seams or laminae of deposit, it is far more injurious, 
and every such seam in a block of stone must sooner or 
later lead to its destruction. The manner of this is very 
simple. The clay seam absorbs water, and, holding it while 
freezing, the seam expands: if disintegration does not 
immediately follow, the seam is widened so that it admits 
more water on the next occasion; and so on succes¬ 
sively with alternate freezing and thawing until an 
unsightly crevice is produced, which constantly widens 
and encroaches more or less on the adjacent parts till the 
stone is destroyed. 

This condition occurs in the gray or light-colored free¬ 
stones, as well as in the brown ones; but in the brown 
freestone or sandstone, there is a farther cause of destruc¬ 
tion. The coloring matter, which is also in part the 
cementing matter of the grains of sand, is ferruginous, 
the siliceous grains are covered with peroxide of iron, and 
this substance is intimately combined with the argilla¬ 
ceous matter of the mass which cements the particles. 
Experience has everywhere proved that the brown sand¬ 
stones or freestones are not durable stones; their de- 
. structibility is not only due to the presence of argillaceous 
matter, but to the oxide of iron ; for the gray or neutral- 
tinted stones, of the same composition otherwise, are much 
more durable. 


Report on Building Stones. 


29 


As an evidence of the rapid decomposition of the red 
or brown sandstone when the siliceous element is defi¬ 
cient, we may sometimes find a large area, which, when 
broken up, decomposes so rapidly that it becomes in a 
few years an arable soil. The same is essentially true in 
some parts of the Medina sandstone. In order to demon¬ 
strate this fact, it is only necessary to examine any build¬ 
ing of brown stone which has been erected for a period of 
twenty-five years. The State Library building is an 
example in point. The Capitol and the Albany Academy 
have been longer erected and were originally of better mate¬ 
rial than the Library building. The basement of the old 
City Hall in New-York is an example of the same kind, 
where the brown stone, from its inherent destructibility 
and from the presence of clay seams, presents a dilapi¬ 
dated appearance; and other examples might be men¬ 
tioned. In Europe the same condition exists, and many 
old buildings of the red or brown sandstone are falling in 
ruins. 

In the lighter-colored sandstones, we have mainly to 
guard against clay seams and too large a proportion of 
argillaceous admixture in the mass. Beyond this, the 
presence of iron pyrites is to be looked for. This mineral 
is present in so many rocks of this character, especially 
those with a bluish or greenish olive tint, that it is to be 

4 

suspected in all such stones. It should be remarked, 
moreover, that iron pyrites (sulphuret of iron), when in 
visible grains, nodules or crystals, is not so dangerous or 
destructive to the rock as when disseminated in fine or 
imperceptible grains through the entire mass. This 
mineral, however, may be so disseminated and not prove 
entirely destructive; since in some stones it decomposes 
from the first exposure to the weather, staining the exte¬ 
rior of a rusty hue, and thus continuing to exude as an 
oxide of iron so long as any of it is reached by the moist- 


30 


Report on Building Stones. 


ureof the atmosphere: at the same time the free sulphuric 
acid unites with the lime or magnesia, if either be present, 
or to some extent with the alumina in the absence of the 
other substances; and this chemical change may sometimes 
go on for along time, without seriously affecting the texture 
of the stone, producing no important result beyond the 
unsightly appearance. Generally, however, the decom¬ 
position of the pyrites produces the gradual destruction of 
the stone. 

We have in the State of Yew-York a class of argilla¬ 
ceous sandstones largely in use as building stones, and 
which are less known in any other State. They are of 
the character of rocks formerly known as “ Graywaeke ,’ 7 
and the name might; be usefully retained to designate the 
argillaceous sandstones of the Hudson-river group, the 
Hamilton, Portage and Chemung groups. These beds of 
the Hudson-river group are known as Blue stone , which is 
a compact argillaceous sandstone consisting of variable 
proportions of these materials. 

The name blue stone is equally applicable to the heavy- 
bedded compact arenaceous layers, and the thin-bedded 
slaty layers, which are largely used in the foundations of 
ordinary buildings. Much of the heavy-bedded slaty rock 
of this character, which is quarried along the Hudson- 
river valley, belongs to the Quebec group; but I am not 
at this time aware of any quarries in the same formation, 
which furnish dressed building stone. 

In the Hudson-river group, this rock occurs in many 
localities, in very regular beds which are cut by vertical 
joints presenting clean straight faces, and are thus laid in 
the building. The composition of these stones (that is, 
in the proportions of silica and alumina) often varies in the 
distance of a few rods ; but, if well selected and laid on 
its natural bedding, it makes a durable building material. 
Much of it, however, becomes stained from the decompo- 


Report on Building Stones. 


31 


sition of iron pyrites, which, after a length of time, either 
leaves the surface of a permanently rusty brown color, or 
the decomposition goes on till the rock crumbles or scales 
off in thin laminae. Sometimes the faces of the joints are 
coated by thin laminae of carbonate of lime, arising from 
the solution and infiltration of calcareous matter; and 
this forms a permanent coating, which resists all farther 
change from atmospheric influences. It is of the greatest 
importance that these stones be carefully selected, or 
otherwise they soon become disintegrated. 

The flagstones so abundantly supplied from the upper 
part of the Hamilton group and lower part of the Portage 
group, are among the most enduring of the compounds of 
silica and alumina. The material is a fine-grained com¬ 
pact argillaceous sandstone of a blue or gra}flsh blue color, 
which, when free from seams, is scarcely influenced by 
the action of the weather. These beds are not only used 
for flagstones in most of the Atlantic cities, but in Albany, 
Troy and other towns along the river and elsewhere, this 
stone is used for doorsteps and caps, window sills and caps, 
water tables, etc. The stone is very strong and durable, 
sometimes slightly staining from the decomposition of 
iron pyrites, but rarely or never undergoing disintegration 
from that cause. 

The blue stone of Malden on the Hudson river, which 
has of late come into use for ashlar door steps and sills, 
pillars or pilasters, window sills and caps, water tables, 
etc., is obtained from some heavier beds in the Portage 
group along the base of the Catskill mountains. The 
stone has great strength and durability, wearing very 
slowly when used for steps, and possessing the great merit of 
retaining a certain degree of roughness of surface. The dark 
color may be regarded as the only objectionable feature. 

In the central and western part of the State, the Portage 
sandstones are of a lighter color, usually more friable than 


32 


Report on Building Stones. 


those of the eastern outcrops. Many of the beds are of a 
greenish or olive-gray color, occurring both in flaggy and 
heavier courses, which are easily dressed and present a very 
good appearance. The frequent presence of iron pyrites, 
causing both staining and disintegration, offers an objec¬ 
tion to their extensive use. In the western counties, how¬ 
ever, some of the beds are nearly gray, having lost the 
greenish or olive color almost entirely, and at the same 
time have les& argillaceous matter in their composition, 
with scarcely a trace of iron pyrites. The stone from these 
beds has a very uniform gray color, a fine texture, and if 
quarried and dried before exposure to the frost, is a very 
durable stone. 

In Ohio, the arenaceous beds of the Portage group fur¬ 
nish the friable gray sandstone from which grindstones are 
largely manufactured, and from which more recently large 
quantities of building stone have been furnished. The co¬ 
hesion of the particles is slight, and the stone is very brittle 
on first quarrying, but becomes stronger and harder on 
exposure, and, if properly selected, resists the effects of the 
atmosphere in a remarkable degree. The strong cohesion 
of the particles, therefore, is not always a requirement for 
(Jurability, though it is for strength, either as resisting 
direct pressure or the effect of tensile force. 

It should not be forgotten, however, that neither all the 
beds of this stone, nor all parts of the same bed, are uni¬ 
form in texture, composition or durability; and it will not 
be surprising, if in its indiscriminate use it may sometimes 
prove unsatisfactory as a building stone. 

The argillaceous sandstones of the Chemung group are 
generally or comparatively free from iron pyrites, and range 
in color from gray to olive or dark olive brown. When 
quarried and exposed to drying before freezing, they are 
comparatively durable stone ; but they cannot be safely 
quarried during winter, or exposed to freezing soon after 


Report on Building Stones. 


33 


quarrying. Building stones from this group, within the 
State of New-York, have long been used, and new quarries 
have been opened at many points, though the stone has 
usually hut a local importance. The more important 
structures erected from this stone are the buildings of the 
Cornell University at Ithaca. 

% 

Manner of Laying. 

Sandstones or freestones, and all the varieties of argilla¬ 
ceous sandstones, should be laid in the building according 
to the natural bedding of the rock, so that the wear of the 
elements may act upon the exposed edges of the laminae. 
Since it is impossible to have any great thickness of stra¬ 
tified stone, especially sandstone, entirely uniform and 
homogeneous in texture, or without interlamination of 

i 

shaly matter, it follows that by turning the blocks upon 
their edges, we shall in one case have the face of a harder 
or coarser layer, and in another of a softer layer of the 
same rock, thus exposing the wall to unequal weathering. 
Not unfrequently the face of the stone is the line of the 
soft shaly parting, and the effects of this practice may often 
be seen in the scaling off of an entire surface of a block of 
ashlar for several square feet in extent. Such examples 
may be seen in some of our buildings, which have been 
erected within the past twenty-five years. Had these 
blocks been laid in an opposite direction, the edges of the 
shaly seams only would have been exposed, and their de¬ 
struction would have been comparatively slow. The sand¬ 
stones separate usually with great freedom along the line 
of hed'ding, and thus offer great facilities for dressing the 
surface in the direction of the laminae ; and from this cause, 
and the desire to present as large a surface as practicable 
in each block, has arisen the practice of setting them upon 
their edges. A block of stone may, however, be split in 

5 


34 


Report on Building Stones. 


the same direction, through one of its more sandy layers, 
and the objections urged may not be so palpable. 

An equally reprehensible practice is the cutting of step- 
stones from blocks with distinct shaly partings, which pro¬ 
duce exfoliation and consequent inequality of the surface. 


Mode op dressing. 

In the use of argillaceous sandstones, as well as some 
other rocks, there are some considerations as to the mode 
of dressing which should not be forgotten. There are 
some stones which, if dressed elaborately, disintegrate 
rapidly upon the surface. This comes from the crushing 
of the material under the tool; * the natural texture and 
cohesion of the particles being thus broken up, it absorbs 
more water, and, on freezing, decays rapidly and becomes 
unsightly. Many stones that are unlit for finely dressed 
work are nevertheless quite durable if rough dressed; 
that is, by dressing the joints close and a smooth space 
along the edge, while the greater part of the face is left 
roughly broken without tool-work of any kind. During 
wet weather, the moisture will collect at the numerous 
projecting points or edges, and much of it drops off which 
would be absorbed by a smooth dressed face of stone. 
The effect of freezing is much less destructive under such 
conditions. Moreover a moderate decree of weather- 

. O 

wearing on such surfaces is less conspicuous than on finely 
dressed stone. The dressing of the stone in the Univer¬ 
sity buildings at Ithaca is a good example of this kind of 
work. 


* The term deadening of the surface is used by the workmen to designate 
this condition. 



Repoet on Building Stones. 


35 


Limestones and Marbles. 

In limestones and marbles, the conditions of durability 
and causes of destruction, as a general rule, differ little 
from those of sandstone. There is nevertheless one point 
of distinction, which may be noted in the outset. In all 
the marbles and older stratified limestones—that is, of 
the Silurian, Devonian or Carboniferous age—the want 
of cohesion among the particles, or a friable condi¬ 
tion of the rock, may be regarded as fatal to its 
durability as a building stone; while on the other hand, 
as lias been observed that some of the friable sandstones 
harden by exposure .to the weather. In the calcareous 
deposition termed travertin , however, which is a deposit of 
modern origin, the mass, on first exposure, is soft , and 
friable, and is frequently cut into blocks of the required 
shape and dimensions by the axe or saw : after being laid 
up in the wall it hardens and becomes quite indestructible. 
Some limestones are said to possess this power of harden¬ 
ing upon exposure. 

In almost all limestones, as well those which are 
unaltered as those which have been metamorphosed and 
are known as Marbles par excellence, there is a consi¬ 
derable amount of argillaceous matter, either present in 
seams parallel to the lines of bedding, or disseminated 
through the mass. In the darker-colored uncrystalline 
or compact fine-grained limestones this matter is evenly 
distributed through the mass, and, when only in small 
proportion, produces no noticeable effect. Some of the 
varieties of this kind of limestone will stand the expo¬ 
sure of a century, without any essential or injurious 
change. The compact fine-grained blue limestones with¬ 
out seams are therefore among the most durable stones 
we have. 


36 


Report on Building Stones. 


In the gray or bluish gray subcrystalline limestones 
the argillaceous matter, instead of being distributed 
throughout the mass, is usually present in the form of 
seams which are parallel to the lines of bedding, or distri¬ 
buted in short interrupted laminae. These seams, whether 
continuous or otherwise, are fatal to the integrity of the # 
stone ; and there is scarcely a limestone structure in the 
country, of twenty-five years standing, which is not more 
or less dilapidated or unsightly, from the effects of ab¬ 
sorption of water by the clay seams, and the alternate 
freezing and thawing. When laid in the position of the 
original beds, which is the usual mode, the separation by 
the clay seam is slower ; but when used as posts or pillars, 
with the lines of bedding vertical, the change goes on 
more rapidly. 

In the dressing of limestone, the tool crushes the stone 
to a certain depth, and leaves the surface with an inter¬ 
rupted layer of a lighter color, in which the cohesion of 
the particles has been partially or entirely destroyed; and 
in this condition the argillaceous seams are so covered 
and obscured as to be scarcely or at all visible, but the 
weathering of one or two years usually shows their 

•a , 

presence. 

The usual process of dressing limestone rather exagge¬ 
rates the cause of dilapidation from the shaly seams in the 
material. The clay being softer than the adjacent stone, 
the blow of the hammer or other tool breaks the limestone 
at the margin of the seam, and drives forward into the 
space little wedge-shaped bits of the harder stone. A 
careful examination of dressed surfaces will often show the 
limestone along the seam to be fractured, with numerous 
thin wedge-shaped slivers of the stone which have been 
broken off, and are more or less driven forward into the 
softer parts. In looking at similar surfaces which have 
been a long time exposed to the weather, it will be seen 


Report on Building Stones. 37 

• • 

that the stone adjacent to the seam presents an interrupted 
fractured margin ; the small fragments having'dropped 
out in the process of weathering. Limestones of this 
character are much better adapted to rough dressing, when 
the blows are directed away from the surface instead of 
against it, and when the entire surface shall he left of the 
natural fresh fracture. By this process the clay seams 
have not been crushed, nor the limestone margining them 
broken, and the stone withstands the weather much 
longer than otherwise. The attempt at fine hammer¬ 
dressing is injurious to any stone; for the cohesion of 
the particles is necessarily destroyed, and a portion of the 
surface left in a condition to be much more readily acted 

upon by the weather. 

# 

The gray, sometimes brownish gray subcrystalline lime¬ 
stone, which is not metamorphic, is usually composed of 
fragments of organic remains more or less comminuted, 
with the interstices filled with fine particles of the same, 
or with an impalpable calcareous mud. In such rocks, 
the fragments of fossils being crystalline, withstand the 
weathering action, while the intermediate portions 
wear away, leaving a rough and sometimes unsightly 

surface. The disintegration from this cause is slow; 

* 

and in the absence of clay seams, a structure of this 
kind of stone may remain a long time without material 
deterioration. 

One of the best limestones of this character, and perhaps 
the best in the country in relation to freedom from clay 
seams, is the encrinal limestone of Lockport, which, at 
that point constitutes a portion of the lower part of the 
Niagara limestone. The Onondaga limestone, in the 
quarries south of Syracuse, is one of ths most useful and 
serviceable of these limestones, and, when free from clay 
seams, is equal to any other limestone in color, quality 
and durability. In some portions of the Onondaga beds 


38 


Report on Building Stones. 


to the westward, and in some similar beds of gray lime¬ 
stone in the Lower Helderberg grouj), the mass requires 
firmness ; and the want of compactness or close coherence 
among the particles allows the infiltration of water, which, 
charged with carbonic acid, acts still farther to lessen their- 
cohesion. 

In some of the Lower Silurian limestones, the entire 
mass of the dark-colored be'ds.is completely penetrated by 
irregular ramifications of siliceous matter, which, in their 
position and relations seem as if they may have been 
fucoidal or spongioid bodies growing upon the bottom at 
the time of the deposition of the calcareous deposits. The 
beds of this character furnish a strong and durable mate¬ 
rial for rough masonry and foundations, and some of the 
beds bear dressing with satisfactory results. 

In the process of metamorphism, the limestones have 
become more or less changed to a white, bluish or grayish 
white color, or to variegated white and gray. The seams 
of argillaceous matter which mark the lines of bedding in 
ordinary limestones have undergone some chemical change, 
and have become chloritic, talcose or micaceous, of a 
greenish, bluish or variegated color, but nevertheless still 
retaining the same relations to the calcareous part of the 
mass as in their normal condition. Although they are no 
longer a clay or shale, but have* undergone some chemical 
change, these parts are nevertheless usually softer and 
weather more rapidly than the surrounding calcareous 
portions; or, if not entirely weathering out, some parts 
of the lines or bands of color are more susceptible to the 
action of the weather, because unevenly disintegrated, 
and finally present an unsightly surface. Bands or stripes 
of color, in all the marbles, indicate a different texture 
and composition from the other parts of the mass, and all 
examples of this character will weather unequally. Such 
stones, therefore, should be used with great caution in all 
structures intended to be permanent. 



Report on Building Stones. 


39 


In some of the marbles there are numerous spots of soft 
talc-like substance, which weathers more easily than the 
surrounding* stone. These will either weather to a dif¬ 
ferent color, or, from softening readily on exposure, give 
opportunity for the growth of minute lichens, thus cover¬ 
ing the stone with dark specks or blotches. Under other 
circumstances these spots may be of different color, but 
scarcely less unsightly, and in the end working the gradual 
dilapidation of the stone. The* white marble of Lee in 
Massachusetts is everywhere marked by these talcy spots, 
and the monuments and gravestones in.the cemeteries of 
the neighborhood are covered with black specks and 
blotches. 

The marbles, however crystalline they may be, are not 
free from the same impurities that affect the unaltered 
limestones; and iron pyrites occurs in these, both as segre¬ 
gated veins or lines of accumulation, interrupted strings 
or nodules, and disseminated in minute particles through¬ 
out the mass. A good example of the latter may be seen 
in some marble at Sheffield in Massachusetts, where the 
stone contains minute particles of iron pyrites, which, be¬ 
coming decomposed on exposure, gives to the entire sur_ 
face a slight rusty hue. The same change supervenes in 
the dressed marble; and some of the blocks in the new 
City Hall of Yew-York show the rusty hue immediately 
after having been laid in the wall. This may be a case in 
which the change will cease after* a time, for want of access 
of moisture to the interior portions, or by the filling of the 
pores with sulphate of lime produced by the decomposition 
of the pyrites,- and thus protecting the deeper portions of 
the stone. 

Besides the ordinary seams or lines of color in the direc¬ 
tion of the bedding, many of the marbles are marked by 
the presence of irregular veins or lines of segregation, which 
are different in composition and texture fromthe surround- 


40 


Keport on Building Stones. . 


ing rock, and though sometimes not very different in color, 
and therefore showing little in the outset, will nevertheless 
usually decompose more readily than the adjacent stone. 
Veins of this kind are of common occurrence in some of 
the marbles used for building, and may be observed in their 
full effect in the State Hall and City Hall of Albany. 
These veins usually consist of some soft talc-like mineral 
with magnesian limestone and iron. The pure white mar¬ 
ble, free from seams or veins of any kind, constitutes the 
smallest part of any or all marble quarries. The columns 
in front of the “old United States Bank,” in Philadelphia 
offer one of the best examples of the destruction of marble 
from the several causes mentioned. Although erected 
scarcely fifty years since, the bedding seams are weathered 
and opened to such a degree as to present an aspect of 
extreme dilapidation, and less than half a century more 
will effect their entire destruction. 

The simple presence of magnesia alone does not neces¬ 
sarily impair the enduring quality of a limestone. Some 
of the hardest and most enduring limestones we have are 
magnesian in character, having such proportions of lime 
and magnesia as constitute a doloYnite. This is the cha¬ 
racter of the Niagara limestone and of some of the older 
limestones of the Silurian series, both in their normal and 
metamorphic condition. As a general rule, however, 
the magnesian limestones, in their normal condition, 
are more friable, more porous and less firm in their cha¬ 
racter than the pure carbonates of lime. The presence of 
iron in magnesiaD limestones, either as an oxide or a 
carbonate of iron, may often aid in hastening their 
decomposition. They usually weather to a brownish hue, 
which is sometimes yellowish or drab-colored, but more 
often, in the unaltered condition, to an ashen gray. The 
yellowish color is due to iron in some form, either as an 
oxide or a carbonate. 


Report on Building Stones. 


41 


In the selection of limestones for structures of any kind 
above ground, care should be taken to avoid the shaly 
seams which are the principal cause of decay; and though 
the stone containing them may endure for many years, 
they yet present an unsightly appearance. We have, in 
the city of Albany, a good example of this in the walls of 
the Reservoir on Eagle street in Albany; and numerous 
other cases of similar character might be cited. In all 
these examples, it may be observed that the dilapidation 
comes from the cause specified, and no other; for in most 
of the structures exhibiting this defect, the tool-marks are 
not yet obliterated from the surface of the solid limestone. 

Limestones of this character, however, are perfectly 
safe and fit for auy foundation or other work placed 
beyond the reach of freezing and thawing; and they 
possess a strength and power of resistance to pressure, 
which fits them for the heaviest structures. 

Although limestones, in their normal condition, as well 
as the marbles, are liable to decay from the action of 
rain-water charged with carbonic acid, yet this cause 
usually operates so slowly on the walls of a building that 
the tool-marks are rarely obliterated in a quarter of a 
century.* The more porous limestones, and some of the 
marbles which notoriously lack cohesive power, may be 
more affected by this action. The liability to be decom¬ 
posed and disintegrated by this process is always suffi¬ 
ciently shown in the natural surfaces of quarries; and in 


* Tlie dark compact limestone at the base of the Lower Helderberg group, 
in some specimens in exposed situations, has retained the tool marks for 
nearly a century ; and lettering cut on blocks of this stone, more than a 
century since, are still fresh and well defined. These examples may be 
seen in an old church in Schoharie, known at as the Old Fort, from having 
been thus occupied during the revolutionary war; and in the Lutheran 
Church near the Court-house, where some lettered stones, from the first 
church erected in that town, have been laid in its foundations. 

6 



42 


Report on Building Stones. 


some cases we find the exposed beds crumbled to a mass 
of sand, while the layers beneath the reach of water and 
frost are comparatively solid.* 


Granite and Granitic rocks. 

In the extensive class of rocks coming under the head 
of Granites, the conditions of durability and causes of 
decay are somewhat modified by the chemical changes 
which have supervened among the original mechanical 
aggregations, and the crystalline character which they 
have assumed. In these rocks we have quartz, felspar , 
mica and hornblende to deal with as simple minerals of definite 
constitution. The quartz or silica is in a crystalline con¬ 
dition. The felspar, a crystalline mineral, is composed of 
a large proportion of silica with alumina and a small pro¬ 
portion of potash, and often a small amount of soda and lime, 
with a trace of iron sometimes amounting to more than 
one per cent. The mica, also crystalline, is composed of 
silica with a larger proportion of alumina than in felspar, 
and a lesser percentage of potash or other alkali, with 
from three to six per cent of iron. The hornblende is 
likewise crystalline, and composed of a large proportion 
of silica with magnesia and lime and sometimes alumina, 
containing also a variable amount of iron, which some¬ 
times reaches to fifteen or even twenty per cent. 

We have therefore no new mineral substance intro¬ 
duced into the compound. The alumina, which was in 
mechanical mixture with the silica in the original stone, 
has combined chemically with a portion of that mineral, 
including also some potash, soda or lime, and thus produced 


* In tliis process, the water dissolves a small portion of the stone as far 
as it reaches, and thus separates the particles still more ; and the further 
access of water, "which freezes in the stone, produces a rapid disintegration 
of the mass. 



Report on Building Stones. 


43 


the felspar and mica. Other portions of the silica, and 
sometimes of alumina, have combined with the magnesia, 
lime and iron, to produce hornblende. All these materials 
have existed in their normal condition in the mechanical or 
sedimentary deposits, and have taken their present form 
through chemical action during subsequent metamorphism. 
These crystalline aggregates may be coarse or fine, and the 
different minerals be present in very variable proportions, or 
even one or two of them absent from the compound. The 
prevailing compounds are of quartz, felspar and mica; or 
quartz, felspar and hornblende. 

The aggregates may likewise be of very different colors, 
the quartz being usually translucent: the felspar varying 
from white to reddish brown; the hornblende, of a dark 
green or black color; while the mica may be of any shade 
from silvery white to a dark brown or black. The pre¬ 
dominance of these, or of any one or two of them usually 
give their hue to the mass. The granites or sienites, in 
which hornblende predominates, are generally of a dark 
color; and those where quartz and felspar predominate 
constitute the lighter-colored granites. 

As a general rule, the granites are more reliable as a 
durable building material than any other class of stones, 
and yet some varieties of them are rapidly decomposed by 
the action of the atmosphere. In these granites where 
felspar greatly predominates, or where this mineral occurs 
in large crystalline masses, there is danger of decomposi¬ 
tion. The action of the weather upon the alkaline con¬ 
stituents of the mineral is the primary cause of the destruc¬ 
tion ; but this change goes on slowly, and, in the walls of 
a building, would scarcely affect the appearance of the 
surface in half a century. The presence of finely dissemi¬ 
nated iron pyrites is often a cause of destruction in the 
gneissoid and granitic rocks. 


44 


Report on Building Stones. 


Some of the fine-grained felspathic granites with mica are 
subject to a slow decomposition or disintegration of the sur¬ 
face, by which thin films are exfoliated. Such examples can 
be seen in some of the older granite buildings of the country. 
Fewer causes of decay are inherent in the ordinary granites 
than in any other stone used in our buildings; and with pro¬ 
per care in selection, a granite structure is comparatively 
indestructible from the usual action of the elements. 

But it should not be forgotten that all the granite of a 
quarry may not be of the high quality desired ; and in this 
rock, as well as in any other, though not usually to the same 
degree, there will be waste and refuse material. Though 
generally more free from iron pyrites than the other rocks, 
yet this mineral does occur in all the granites, and there is 
rarely a building erected that does not show its presence ; 
but in all the quarries examined, from which building-ma¬ 
terial is obtained, this mineral occurs only in scattered and: 
inconsiderable amounts. 

In those granites where the crystalline mixture consists 
of fine or moderately coarse grains of the different sub¬ 
stances intimately miugled throughout the mass, we may 
count upon a durable building material, and one subject to 
a less degree of change from atmospheric agencies than 
any other stone in our country. 


VII. Modes of determining the character and strength 

OF BUILDING STONES. 

In the erection of all public structures, or those of any 
considerable magnitude, the strength and durability of the 
material is of the first importance, and that which should 
receive the most careful attention. In large and heavy 
structures the strength of the material is of more import¬ 
ance than in ordinary ones, which never approach a test of 


Report on Building Stones. 


45 


the strength or power of resistance of the material compos¬ 
ing them. Even with all the experience we have had, and 
the experiments that have been made, there seems to be no 
settled opinions or knowledge among engineers regarding 
the real strength of the various kinds of stones, either in 
regard to their direct resistance of pressure or their lateral 
strength. According to the report of Prof. Henry, the 
Commissioners appointed to test the stone preparatory to 
the erection of the extension of the United States Capitol, 
found that the practice heretofore adopted for testing the 
strength or resistance to pressure was very defective, and 
the results unsatisfactory. If the result thus obtained be 
admitted, and of which there can be no doubt, the state¬ 
ments heretofore recorded on these points, and the tables 
compiled from the experiments made, are to be regarded 
with many grains of allowance in favor of the stone tested. 
While the instruments employed by Rennie and others were 
defective, the plan of placing the block of stone to be tested 
between steel plates with a sheet of lead intervening, in 
order to equalize the pressure from irregularity of the sur¬ 
face of the stone, or want of parallelism in the opposite 
faces, gave very imperfect results. 

In experiments reported by Prof Henry, we have the 
example of a cube of marble placed between steel plates, 
with lead intervening, giving way at a pressure of 30,000 
pounds; while another block of precisely similar character 
placed directly in contact with the steel plates, sustained 
a pressure of 60,000 pounds. “This interesting fact was 
verified in a series of experiments embracing samples of 
nearly all the marbles under trial, and in no case did a 
single exception occur to vary the result. The explana¬ 
tion of this remarkable phenomenon, now that the fact is 
known, is not difficult. The stone tends to give way by 
bulging out in the centre of the four perpendicular faces, 
and to form two pyramidal figures with their apices opposed 


46 


Report on Building Stones. 


to each other at the centre of the cube, and their bases 
against the steel plates.” 

“In the case where rigid equable pressure is employed, as 
in that of the thick steel plate, all parts must give way to¬ 
gether ; but in that of a yielding equable pressure, as in 
the case of interposed lead, the stone first gives way along 
the outer lines, or those of least resistance, and the remain¬ 
ing pressure must be sustained by the central portions 
around the vertical axis of the cube,” This fact, so clearly 
demonstrated, shows very conclusively that all experiments 
made upon blocks of stone with the intervening yielding 
material are fallacious, and really give us but one-half the 
actual power of resistance possessed by the stone tested. 
When we add to this fact also the practice of engineers as 
usually stated, that owing to imperfections of the material 
and other causes, it is not considered safe to load a stone 
with more than one-eighth of its crushing weight,* it will 
be seen that we are very far within the safe limits to which 
any stone may be loaded and retain its integrity. 

By this process, Prof. Henry has shown that the marble 
of Lee, Massachusetts, will sustain a pressure of 23,917 
pounds to the square inch. This marble was adopted for, 
and has been used in the Capitol extension or Hew Cap¬ 
itol in Washington. In strength it is not superior to many 
other marbles, nor equal to some of the ordinary compact 
limestones, and is much inferior to the granites. In com¬ 
position it consists of the carbonates of lime and magnesia, 
and is a true dolomite, as shown by the analysis of Dr. Gentii 
and Dr. Torrey ; containing minute proportions of iron and 
manganese. The experiment of using a dolomite on so 
large a scale will ultimately demonstrate whether a stone 
of this composition can be relied upon as a durable building 


* According to some engineers with but one-twentieth of its crushing 
weight. 



Report on Building Stones. 


47 


material. As before stated, however, the simple presence 
of magnesia is not of itself evidence of the rapid decay of 
the stone: a small proportion of iron in some form, or 
combined with some other mineral, may effect the destruc¬ 
tion of a magnesian limestone that otherwise appears sound 
and durable. 

Less attention seems to have been given to the lateral 
strength of stone, than its importance would warrant. 
When we see, even in buildings of recent erection, the 
window sills and caps cracked through, and these parts 
giving way and becoming dilapidated and unsightly, it is 
evidently a matter of no small importance to be able to 
decide what amount of weight can be borne by stones of 
certain dimensions. This knowledge also becomes of the 
highest importance in view of the manner in which the 
foundations of heavy buildings are laid; the gradual re¬ 
traction of the width above relieving the lower and outer 
layers of stone from the direct crushing force of the super¬ 
incumbent walls, but testing its lateral strength.* 

In estimating the strength of a stone to resist pressure, 
it is not always safe to predicate an opinion upon examples 
of cracking or breaking in the walls of a building, whether 
before or after its completion ; for a little inequality in the 
bedding may produce such a result, when, if evenly bedded, 
the stone would have borne many times the load it has 
sustained. In a large and heavy building it is all import¬ 
ant that the foundations be firm and unyielding, for on this 
depends the integrity of the entire structure. Beyond this 
it is important that the stone be evenly cut, so that the bed 
of each succeeding block should rest evenly upon those 
below it. From an inequality in dressing two adjacent 
blocks of stone to the same thickness, leaving at their 
junction one of them projecting slightly beyond the other, 

* The results of experiments, showing the power of resistance to pressure 
of several of our limestones, marbles, granites, etc., will be found in an ap¬ 
pendix to this Report. 



48 


Keport on Building Stones. 


I have seen the superincumbent block of granite cracked 
quite through. This breaking was not due to pressure 
alone, nor to want of strength in the material, as was evi¬ 
dent from the perfection of the walls below, but entirely to 
the pressure bearing upon the centre of a block resting on 
an uneven bed, or supported at the two ends and not in the 
centre. 

YIII. Causes affecting the durability of a building 

STONE, WHICH ARE INHERENT IN THE STONE ITSELF. 

The causes of disintegration and destruction in the 
ordinary building-stones have already been mentioned 
under each one. They may be recapitulated, however, in 
this place. 

1. Want of proper cohesion among the particles producing 
inherent weakness. This condition may arise from the 
loose aggregation of the crystalline grains of carbonate of 
lime, or of the compound of carbonates of lime and mag¬ 
nesia, sand, etc., without intervening cement, or from 
want of the pressure necessary to consolidate the mass. 
We have examples of this in the friable marbles and some 
sandstones. In some cases this condition occurs where 
the rocks have been much disturbed since their deposition 
and partial or entire consolidation. But this condition 
as frequently occurs in rocks which, so tar as we know, 
have not been subjected to change, and lie in their ori¬ 
ginal horizontal position. One of the most remarkable 
examples occurs in the western extension of the Potsdam 
sandstone; much of which, in some parts of Wisconsin 
and Minnesota, may be easily quarried with pick and 
shovel, and readily crumbles into an incoherent sand. 
Above the Potsdam, the St. Peter’s sandstone has still less 
coherence, and is shovelled out in the same manner as 
the ordinary sand of the drift or of the sea beach. From 


Report on Building Stones. 


49 


this incoherent condition of the mass, we have all grada¬ 
tions to the most strongly coherent rock. This condition 
of the particles, be it in greater or less degree, affects 
the strength and durability of the stone. 

Blocks of stone, wanting proper cohesion, may crack or 
he partially crushed by superincumbent weight; but or¬ 
dinary judgment will guard against using such improper 
material. The cohesion of the particles or grains com¬ 
posing a stone does not depend upon their hardness or 
density ; for the grains or crystals composing a mass of 
marble, and having half the density of grains of sand, 
often produce a stronger stone than one made up of the 
better material. 

2. Porosity . The porosity of a stone is, in most in¬ 
stances, directly dependent on the degree of cohesion 
among the particles. Crystalline masses are usually less 
porous than mechanical aggregations; and where the 
interstices between the crystals are filled with finer material, 
it has been shown that the latter is porous and absorbent, 
while the former resists the penetration of fluids. In 
some of the crystalline limestones, the cohesion is so 
slightJ;hat the water admitted, and freezing, has gradually 
broken up the mass, and we have a bed of calcareous 
sand, of several feet in thickness, lying above the rock 
which yet retains its ordinary consistence. Some of the 
fine-grained and compact mechanical aggregations of rocks 
resist the absorption of water in a remarkable degree. 

3. Argillaceous matter in distribution or in seams. I have 
already shown that the presence of a considerable propor¬ 
tion of argillaceous matter distributed throughout the mass, 
be it calcareous or siliceous, has a tendency to weaken 
and destroy the stone. Its presence in seams or thin 
laminae produces the same result, as we have numerous 
examples to show. 

7 


50 


Report on Building Stones. 


4. Iron 'pyrites (sulphur et of iron) and other foreign substances . 
Iron pyrites (sulphuret of iron), whether intimately per¬ 
meating the stone or occurring in masses, layers or irregu¬ 
lar nodules, is more or less injurious and destructive. 
When not immediately destructive, its decomposition 
renders the surfaces unsightly by staining the stone, and 
finally breaking or disintegrating it wherever this mineral 
occurs. When disseminated through the mass, as it fre¬ 
quently is, it produces slow but entire disintegration. 

It is not an uncommon thing to find masses of rock, in 
their native position, completely disintegrated or softened 
to the depth of several feet by decomposing iron pyrites. 
This feature is especially observable in the Gold region 
of Virginia, Rorth-Carolina and other Southern States. 
In numerous instances, and sometimes over wide areas of 
country, the rocks containing iron pyrites are decomposed 
by percolating rain water, to the general water-level of 
the surrounding country. 

In limestones or dolomites, the presence of iron pyrites 
operates disastrously; for if magnesia be present, the 
sulphuric acid from the decomposing iron pyrites produces 
a soluble efflorescent salt, which exudes to the surface 
and forms white patches, which are alternately washed 
off and replaced, but leaving a whitened surface probably 
from the presence of sulphate of lime. If the limestone be 
entirely calcareous, the salt formed (a sulphate of lime), is 
insoluble, and therefore produces less obvious results. 

In some cases, however, the lime of which the mortar 
or cement is made may contain magnesia, and the decom¬ 
position of the iron pyrites in the adjacent stone produces 
an efflorescent salt which exudes from the joints. This 
condition is not unfrequently observed in buildings con¬ 
structed of the blue stone of the Hudson-river group. As 
an example, we may notice the efflorescent patches pro¬ 
ceeding from some of the joints between the stones of St. 
Peter’s Church on State street in Albany. 


Report on Building Stones. 


51 


The presence of iron in a low degree of oxidation tends 
to the destruction of the stone containing it. This is 
observed in the greenish shales and sandstones and in 
some other rocks; and this condition of iron, as well as 
in the form of a sulphuret, may do much injury where it 
exists. 

5. Size of constituent grains or particles. This feature has 
already been alluded to under the head of granites, sand¬ 
stones, etc. When the separate minerals of a granite are 
in large crystalline masses, it is an objectionable feature 
and a cause of decay. Coarse sandstone, ora mixture of 
fine grains of sand with pebbles of various sizes, does not 
usually endure well. Similar sandstones or conglomerates, 
when partially metamorphosed, and cemented by silica, or 
some siliceous compound, are less affected by the weather 
and are more durable. In the crystalline marbles, some of 
the coarser varieties are weak from the want of cohesion or 
cementing matter between the crystals. The same is 
equally true occasionally of those which are more finely 
crystalline ; and we sometimes find a coarsely crystalline 
marble stronger than a finer one, in similar beds but a few 
miles asunder, or even beds in the same quarry may differ 
in this respect. The coarsely crystalline marble of Tuck- 
ahoe is stronger than the finer-grained marble of Singsing 
and other places in the neighborhood. So far as the mar¬ 
bles are concerned, all the crystalline forms, be they coarse 
or fine, may be strong or weak. The fine-grained marbles, 
which show scarcely a crystalline structure, or such only as 
the calcareous muds might take on in their metamorphism, 
are the most durable stones of this kind. 

6. Cementing materials. I have already alluded to this 
feature under the preceding head. When the cementing 
material is clay, or where argillaceous matter predominates, 
it is rapidly disintegrated by the absorption of water, and 
freezing and thawing while thus saturated. Where the 


52 


Report on Building Stones. 


cementing matter is calcareous, it will dissolve more slowly, 
and only through the agency of rain water carrying carbonic 
acid. Where the cement is siliceous, it is essentially inde¬ 
structible from the effects of the atmosphere and water. 

The cementing material of the Tertiary sandstones of 
which the Old Capitol, Treasury and other buildings 
in Washington were constructed, is clay and carbonate 
of lime, and its rapid disintegration from rain and frosts is 
always observable. As before noticed, some friable sand¬ 
stones become harder on exposure, and this change has 
been presumed to be due to the formation of a siliceous 
cement on and near the surface. Sometimes p>robably a 
silicate of lime, or a small quantity of calcareous matter 
held in solution in the interstices of the stone, may become 
precipitated as solid carbonate of lime, in accordance to a 
well-known law, on exposure to the atmosphere. 

Every geologist knows that not only sandstones, but all 
other rocks are more easily shaped and trimmed when 
freshly broken from the ledge or quarry, than after they 
have remained for some time exposed to the atmosphere 
or even carefully packed. The hardening or toughening 
process, however, extends but a little way beneath the sur¬ 
face, and the interior of a block remains essentially as when 
first quarried. 


IX. Causes affecting the durability of a stone, which 

ARE ACCIDENTAL OR DUE TO ARTIFICIAL OR EXTRANEOUS 

CONDITIONS. 

Many stones, which with proper treatment or under 
favorable circumstances might prove a durable building- 
material, are brought to a rapid decay by conditions to 
which they are subjected in the structure. 

1. The action of freezing and thawing. This alternating 
process of freezing and thawing is the most trying to the 


Report on Building Stones. 


53 


durability of a stone, of any or all the conditions to which 
it is subjected. Of course this depends upon the climate 
or latitude in which the stone is exposed. The Caen stone 
of Normandy, and some of the less coherent limestones of 
modern geological formations, are strong enough and quite 
durable for buildings in Southern Europe or where the 
frosts are not extreme; but in a climate like our own, they 
are rapidly destroyed by the alternate action of freezing 
and thawing. 

Some of the finer sandstones, which have a considerable 
amount of argillaceous matter, are perfectly capable of with¬ 
standing moderate freezing; but the extreme changes from 
a moist condition, or one saturated with moisture, to the 
extreme of freezing, are fatal to their durability. 

As before repeated, any stone in which clay enters largely, 
or a porous stone of any kind, is liable to decay under the 
extremes of wet and frost. The penetration of moisture 
among the particles of the stone, and its expansion on freez¬ 
ing, destroy the cohesion of the parts, and the succeeding 
rains wash away the loosened particles. In this way, during 
a long succession of years, the surface is disintegrated and 
the structure gradually crumbles. Although some stones 
are more susceptible to these atmospheric influences than 
others, yet none are entirely free from its effects. 

Even the changes of temperature, without frost or 
moisture, operate upon the masses of stone and cause a 
motion of the particles. The observations of Prof. Hors- 
ford upon the pendulum suspended within the Bunker-hill 
Monument show that this massive structure “ is scarcely 
for a moment in a state of rest, but is constantly working 
and heaving under the influence of the ever varying tem¬ 
perature of its different sides.” When to this is added the 
extreme action of freezing and thawing, it can not be sur¬ 
prising that the poorer materials will fall into dilapidation, 
or that the best selected building-stone will ultimately give 


54 


Keport on Building Stones. 


way. This cause operating everywhere, at all times and 
through all seasons, is a far more active agent in the de¬ 
struction of buildings than all the others operating together; 
and though it may sometimes require years for an appreci¬ 
able change to be accomplished upon a sound material, it 
is nevertheless constantly going on, however slow the 
change may be. 

2. The improper laying of stone by presenting the faces 
of laminae to the weather, often hastens the disintegration 
of the mass. I have already alluded to this, especially in 
regard to the brown free-stone which is now so extensively 
used, and which presents such uneven weathering, from 
being in part laid according to the bedding, and in part 
with the bed facing the exterior. 

3. The vegetation of microscopic lichens takes place upon 

the surface of the stone, when, from any cause, that surface 

becomes roughened so as to afford a lodgment for the seeds 

or spores of these plants. These growing, still farther 

hasten the disintegration of the stone, and accumulating 

about them the fine dust floated by the atmosphere, become 

• 

points for the absorption of more water, which on freezing 
still farther roughens the surface, and the patch of lichen 
gradually extends. These lichens often gain attachment 
upon the surface of a finely dressed stone, from some 
little inequality of texture, or from softer material that 
more readily becomes decomposed, or more readily ac¬ 
commodates the growth of the plant. Such stones in time 
become partially or entirely covered by lichens, and pre¬ 
sents an unsightly aspect. The amount and degree of 
this growth varies with position in reference to the sun, 
and with a more or less elevated situation. 

It should not be forgotten, however, that any stone 
giving root to lichens is not one of those which most 
easily disintegrate; for in these the destruction goes 
on so rapidly, that the surface does not allow the 


Report on Building Stones. 


55 


growth of such plants. The lichen-covered rocks in 
nature are usually those of great strength and durability. 
Rone of the softer or rapidly decaying rocks produce this 
vegetation. 

4. The solvent action of water is never so great upon arti¬ 
ficial structures, as upon the rock in its natural position; 
for in the latter case, it is usually aided by a covering 
of soil, through which the water is filtered ; and if not 
thus covered, the rock is exposed in broad surfaces to 
much greater action than in the walls of a building. 

5. The oxidizing influence of the sun’s rags is only con¬ 
siderable when aided by moisture, and in this condition 
scarcely operates except upon iron pyrites and iron in a 
low state of oxidation. 

6. The effect of electricity. Prof. Henry, after citing the 
effects produced by water charged with carbonic acid, 
says: “Again, every flash of lightning not only gene¬ 
rates nitric acid — which, in solution in the rain, acts 
upon the marble — but also by its inductive effects at 
a distance, produces chemical changes along the moist 
wall, which at the present time are beyond our means 
of estimating. ” 

T. Effects from sulphurous gases produced by burning coals. 
In the unexpected gradual dilapidation of the New Houses 
of Parliament in London, the causes have been sought 
and apparently found in an agent heretofore little regarded 
as one producing serious deterioration of buildings. The 
stone is a magnesian limestone from Bolsover moor, 
and was selected as having been found to retain its 
integrity and to have preserved in a very perfect degree 
some of the carvings in Southwell church through a 
long period of time. 

The same material, and from the same locality as stated, 
has been used in London with a very different result. 
An examination made a few years since led to the belief 



56 


Report on Building Stones. 


that this disintegration of the stone was caused by the 
action of sulphurous vapors arising from burning coals; 
which lodging with the soot against the sides of the build¬ 
ing, and especially in sheltered positions under the project¬ 
ing eaves and mouldings, and thus remaining saturated with 
moisture under the most favorable conditions for acting 
upon the stone. To this cause, in London, we may attri¬ 
bute some portions of the effects observed in this and other 
examples. Now it should be recollected that in this 
densely populated city, with its proverbial “London fogs,” 
and the burning of bituminous coal, the rising of the soot 
and its condensation on the side of buildings during 
the heavy damp weather and fogs, would, as a matter of 
course, produce some effect upon the stone. 

Such conditions, however, can scarcely exist in any 
Atlantic city (even if in any American city), with our drier 
atmosphere and the sulphurous gases mainly from anthra¬ 
cite coal, which gives no soot. In the Ohio and Missis¬ 
sippi valleys, where bituminous coal is burned and the 
soot lodges against the buildings, we might possibly look 
for some effect; but the comparative dryness of the atmo¬ 
sphere would probably counteract the otherwise evil effects 
from this cause. In considering this cause of deteriora¬ 
tion, we shall find it only applicable to special localities ; 
and even in these it may be well to inquire whether other 
causes have not combined with this one, to produce the 
results recorded.* 

* It may perhaps be worth while to inquire whether the effects ascribed 
to sulphurous gases are really due to such influences alone. 

A writer in the “ Builder ” for Oct. 30th, 1858, says that the river front, 

“ to the height of the area windows was built of the Bolsover moor stone, 
but that the remaining upper part, to my wonderment, was built of stone 
obtained from Anston in Yorkshire, a stone not even alluded to in the 
Report,” i. e., the Report of the Commissioners. 

If this be true, the theory adopted in explanation of the cause of decay 
may require some modification. 



Report on Building Stones. 


57 


I have received From Prof. J. P. Lesley, of Philadelphia, 
the following observations regarding the influence of cli¬ 
mate in different localities, upon stone of identical or 
similar character. In speaking of the durability of stone 
in ancient structures it becomes necessary to know the 
conditions of climate before a just comparison can be 
made. '> A » . ■■ ; . 

“ One of the two obelisks erected by Thothmes III, at 
Heliopolis fifteen or sixteen centuries before Christ, was 
transferred to Alexandria and is now known as Cleopatra’s 
Needle. It is of sienite, so streaked with hornblende, 
obliquely, as to suggest original stratification. Along 
these streaks, which are of irregular width, atmospheric 
erosion has taken place, by the ejection of one group of 
crystals after another, upon the melting away of the fels- 
pathic element. * The whole face of the stone has suffered 
from the same action, but generally to a less degree, than 
at these exceptional places. Especially all the sharp cut 
edges have been rounded off. Wherever the solar disc, 
for instance, occurs, there is now nothing but an unsightly 
hollow, where originally had been cut a sharp clear circle, 
with a vertical wall around a central convex tympanum. 


thus : 
now : 



All the hieroglyphs from pyramidion to base have suffered 

in this way. Some are almost indistinguishable, except 

in the very best slanting light of the sun. One or two of 

the four faces also, have suffered more than the others, 

showing that the prevailing winds have determined the 

decree of erosion. The climates of Cairo and Alexandria 
& 

are so different from one another, the former so constantly 

8 









58 


Report on Building Stones. 


dry and the other so uninterruptedly wet, that we have a 
right to ascribe the most of this destruction to the sea air 
since the removal of the obelisk from its original to its pre¬ 
sent site. But all the monuments of Egypt, at least up to 
the first cataract, show marks of atmospheric erosion, in spite 
of the loose assertion often repeated by travelers, that they 
are as fresh and their lines as sharp as when the chisel 
cut them. This is not true of any monument in the open 
air; but is approximately true of the intaglios in the 
tombs. Many of the monuments of the middle and classic 
empires are built of such inferior kind of stone, the only 
wonder is that they have not tumbled into ruin of them¬ 
selves, through the slow wear and tear of the surface, by 
the atmosphere. And yet Egypt is one of the driest parts 
of the world. It must be remembered, however, that the 
stratum of air which lies at night upon the broad bottom 
of the valley, is charged with the exhalations of the river, 
canals and irrigated fields, and in this stratum the monu¬ 
ments stand. When the sun rises this moist air-mass is 
broken up and carried over the mountain walls into the 
desert.” 


X. Results of the trials of the strength of some of 

THE SPECIMENS SUBMITTED TO THE CAPITOL COMMISSIONERS, 

made at Washington in Xovember, 1868. 


Specimens of the gray gneiss of Saratoga county of one 
inch cubes placed between steel plates, sustained a pres¬ 
sure of from 16,800 to 25,600 pounds; the lowest number 
doubtless from imperfection. The average of these speci¬ 
mens gave 22,666 pounds as the crushing weight per 
square inch. 


Keport on Building Stones. 


59 


Of the dark colored sienite, the range was from 18,000 to 
2o,700 pounds as the crushing weight; the lowest number in 
this case, resulting from the want of entire parellelism in 
in the two faces of the cube. The average of four speci¬ 
mens gives 22,575 pounds as the crushing weight per 
square inch. 

A single cube of one and a half inches, from one of the 
beds of Tribes Hill limestone, sustained a pressure of 
66,300 pounds, or 25,022 pounds to the square inch, before 
breaking. A similar specimen from another layer of the 
same limestone, sustained a pressure of 54,400 pounds, or 
24,622 pounds to the square inch. 

Three specimens of limestone from the Cobleskill quar¬ 
ries, in blocks of one and a half inch cubes, gave a range of 
from 51,000 to 72,700 pounds of pressure before breaking, 
being an average of 27,407 pounds to the square inch. 
A single cube of one and a half inches from another bed 
of the same limestone, gave 21,066 pounds as the crushing 
weight, to the square inch. 

Three specimens of compact white marble from Alford, 
Mass., in one and a half inch cubes, sustained respectively 
26,300, 26,900 and 27,000 pounds before breaking, giving 
very nearly 12,000 pounds as the crushing weight, per 
square inch. 

These experiments sustain the opinion previously ex¬ 
pressed in my report, that these compact limestones are 
stronger than the marbles, and equal to many of the 
granites. 

In regard to the lateral strength of these stones, we 
have a right to infer from the close grain and compact 
texture, as well as tenacity shown in the process of crush¬ 
ing, that they are also superior in that character. 

I may remark in this place, that the stone used in the 
new Capitol foundations at Washington, is gneissoid rock 


60 


Beport on Building Stones. 


or mica slate, and lias not the strength of the gneiss and 
limestones here recorded. 

f The remaining collection of specimens submitted for 
trial have been left with Prof. Joseph Henry, and the 
results of the experiments will be reported at a future 
time. Very respectfully, 

Your obedient servant, 

r 

James Hall. 


Note. The remarks upon the red or brown sandstone 
(freestone), are mainly based upon an experience of the 
Connecticut river stone and a smaller degree upon that 
from New-Jersey. The sandstone of the same age on the 
Potomac river, in Maryland, known as the Seneca creek 
sandstone* has in many examples proved extremely dura¬ 
ble ; and 1 have been shown a specimen of this rock, taken 
from one of the old locks on the river where it has been 
exposed to the elements for eighty years, and the stone is 
still sound. The specimen, however, is very compact, 
highly siliceous, and with no visible seams of argillaceous 
matter. 

The observations made upon buildings already erected 
of different material, have been, with few exceptions, 
omitted from the present report, but may be published 
at a future time. Probably no better service could 
be rendered to the future architecture of the country 
than an unsparing exposition of the condition of various 
buildings and public edifices erected of stone. When 
it is considered that very few of these have existed 
for fifty years we shall be prepared to appreciate the 
extreme dilapidation and ruin which must ensue within 
the next century. 

The map presented with the report is colored to show 
the sources of the several kinds of building stone, as 


Report on Building Stones. 


61 


Granite, Marble, Sandstone, etc., in New York and New 
England, but it will not be published at the present time. 

The author begs the indulgence of his friends and the public, in 
offering so incomplete a report upon a subject of so much import¬ 
ance as that of the building stones of the State and country. The 
investigation requires much more time to make the result at all 
worthy of being presented in printed form : this time, it has not 
been possible to give during the past year, and the publication at 
this moment is beyond his control. The matter has all been put in 
type and the first thirty-two pages printed off during the absence 
of the writer, in consequence of which several typographical errors 
have occurred. The memoranda in the margins of some of the pages 
were made for the writer’s use in giving an abstract of the report, 
and were not intended for printing. 


n j „ 

XI. Catalogue of the principal building stones in the 

COLLECTION WHICH HAVE BEEN SUBMITTED TO THE COMMIS¬ 
SIONERS FOR THEIR INSPECTION, OR WHICH HAVE BEEN 
COLLECTED DURING THE EXAMINATION OF QUARRIES. 

A. Granites and Granitic Rocks. 

< . ■ i • ■ • . 1 

1. Quincy Granite. Dressed block of one cubic foot. 
Old Quincy quarries, from the Quincy Railway Grauite 
Company. 

2. A smaller dressed block of the same, brought from 
the quarry at time of examination. 

3. Quincy Granite. Light colored, a small block par¬ 
tially dressed, brought from the quarries of Rogers & Co. 

4. Gray Granite. A rough block, brought from the 
quarries at Rockport, Cape Ann, Mass. 

5. Porphyritic Granite. A block six by twelve inches 
partially dressed: Fall River, Mass., from Geo. Wrightson, 
Esq., of New-York. 

6. Gray Granite. Dix island, Maine: from Messrs. 
Learned & Dickson. 


62 


Report on Building Stones. 


7. Gray Granite. Concord, Yew-Hampshire, a dressed 
block of one cubic foot, from the Quincy Railway Granite 
Company. 

8. Gray Granite. A cubic block of six inches square 
from the same. 

9. Gray Granite. Eitzwilliam, Yew-Hampshire, a 
dressed block of one cubic foot, from Runels, Clough 
&; Co. 

10. Gray Granite. Berlin, Vermont; a dressed block 
of ten inches square, from M. E. Howard. 

11. Gray Granite. Barre, Vermont; a dressed block of 
one cubic foot, from Mr. 1. P. Harrington. 

12. Gray Granite. Barre, Vermont; a dressed block of 
one cubic foot. 

13. Gray Gneissoid Granite. Greenfield, Y. Y.; a 
dressed block of one cubic foot, and two dressed blocks of 
six inch cubes with several larger rough blocks of the same, 
from John H. White, Esq., and Hr. R. L. Allen of Saratoga 
Springs, Y. Y. 

14. Hark Colored Sienite. Greenfield, Y. Y.; a 
dressed block of one cubic foot and. two other blocks of 
six inch cubes, one of the latter polished on two sides. 

15. Gray Gneissoid Granite. Luzerne, Saratoga Co., 
Y. Y.; a dressed block of one foot by two feet, from Col. 
B. C. Butler of Luzerne. 

16. Gray Gneissoid Granite. Several rough blocks 
from Moreau, Y. Y.; from Mr. W. B. Conant. 

17. Gneissoid Granite. Luzerne, Y. Y.; a block of two 
feet long, twenty inches wide and one foot thick, from 
Hr. R. L. Allen. 

18. Gneissoid Granite. Butter Hill, Highlands, Y. Y.; 
a rough block, from Hon. A. M. Sherman of Yewburgh, 
Y. Y. 

19. Light Gray (nearly White), Granite. Specimen 
of 12x8x2 inches, cut and partially polished. Said to be 


Report on Building Stones. 


63 


from St. Albans, Yt. ; but believed to be from Berlin, 
Yt. From Mr. Charles E. Young of Oswego, H. Y. 

20. Sienite. Two rough specimens from Warren 
county; from Mr. John Higgins of Troy, Y. Y. 


B . Marbles of White or Variegated Colors, Metamorphic 
and Crystalline in Character. 

21. Yariegated and Monumental Marble. Sutherland 
Falls, Yt.: one dressed and partly polished block of one 
cubic foot; three blocks of one foot face by six inches 
thick, polished on one face ; one block of one foot face by 
six inches thick, one face sand-rubbed and moulded ; 
one block of 12x12x10 inches, one face polished; two 
blocks of six inch cubes polished and variously dressed. 
These specimens were all presented by the Otter Creek 
Marble Co. 

22. Berkshire Marble, Silver Blue Marble. Al¬ 
ford, Mass.; one block of a cubic foot, variously dressed 
and polished on one side. 

23. White, or slightly clouded Marble. Lakeville, 
Connecticut; a block of one cubic foot, dressed with one 
side polished: from H. Tudor Brownell, Esq. 

24. Marble. Bluish or dove-colored, Lakeville, Con¬ 
necticut ; a cubic block of one foot, two faces polished: 
from H. Tudor Brownell,-Esq. 

25. White Marble. Sheffield, Mass.; a block of 
10 xl0x8 inches, one side polished: from one of Mr. 
Chester Goodale’s quarries. 

26. Clouded Marble. Sheffield, Mass. A block of 
one cubic foot, one side polished; same as the marble 
used in the Girard College. Quarry of Mr. Chester 
Goodale. 


64 


Report on Building Stones. 


27. Striped Marble. Sheffield, Mass.; a block of one 
cubic foot, one side polished. Quarry of Mr. Chester 
Goodale. 

28. White Statuary Marble. West Rutland, Ytt 
Dressed block of one cubic foot, one side polished. 

29. Striped Marble. . West Rutland, Yt. 

30. Brocatella Marble. West Rutland, Yt. 

31. Marble, Muddy Layer. West Rutland, Yt. 

32. Striped Marble. West Rutland, Yt. The pre¬ 
ceding five specimens are blocks of one cubic foot 
each, three of the lateral, faces dressed in various modes 
with one face polished, the upper side showing the 
fracture of the stone. These blocks are from the new 
quarry of Sheldon & Slason, presented by the owners 
through W. C. Rowell, Esq., of Rutland. 

33. White Crystalline Marble. Tuckahoe, H. Y.; 
a dressed block of one cubic foot, one face polished, the 
upper side showing fresh fracture : from Masterton & Hall. 

34. White Crystalline Marble. Tuckahoe, H. Y.; 
a cubic block of six inches square, one face polished : from 
Masterton & Hall. 

35. Clouded Marble. A block of 10x7x5 inches, 
dressed, with one face polished. 

36. Clouded Marble. A dressed block of 8x5x4 
inches (blocks 54 and 36 have been received as coming 
from Duchess county, particular source unknown). 

37. Clouded Marble. A dressed cubic block of six 
inches square, one side polished; from the Berkshire 
Marble Company, Alford, Mass. 

38. White Crystalline Marble. A dressed block of 
12x8x6 inches, with one face polished: locality un¬ 
known, probably Tuckahoe or Hastings, N. Y. 

39. White Marble. A dressed block of 9 x 9 x 6 inches, 
locality unknown. 


Report on Building Stones. 


65 


40. Clouded Marble. A dressed block of 6x6x9 
inches, locality unknown.* 

41. White Crystalline Marble. A dressed block of 
16x12x8 inches, with one face polished : from the state 
quarries at Sing Sing. 

42. Gray Crystalline Marble. A dressed block of 
one cubic foot, one face polished : Hastings, Y. Y. 

43. White Marble, coarsely crystalline. A dressed 
block of ten inches cube, one side polished : Hastings, 

Y. Y. 

44. Gray Marble. A block of 12 x 12 x 18 inches, two 
sides dressed ; from Stockbridge, Mass. 

45. Serpentine Marble, Yerd Antique. A dressed 
block of eleven inches cube, with one face polished; from 
the quarry of Mr. Walton, Port Henry, Y. Y. 

46. Serpentine Marble, Yerd Antique. Port Henry, 

Y. Y. A specimen dressed as a pillar with square base of 
9x9 inches and 15 inches high, moulded above, with cylin¬ 
drical shaft of two feet high ; from-Sherman, Esq., of 

Port Henry, Essex county, Y. Y. 

47. Serpentine Marble, Yerd Antique. A rough 
slab of 12 x 18 x 4 ; Port Henry, Essex county, Y. Y. 


C. Limestones not Metamorphic. 

48. Gray Limestone. Lockport, Y. Y.; a finely dressed 
block of one cubic foot, from B. & J. Carpenter. 

49. Hark Blue Limestone. A dressed block of one 
cubic foot, with one side polished : from James Shanahan, 
Tribes Hill, Y. Y. 

50. Hark Blue Limestone. A rough dressed block of 
one cubic foot; from James Shanahan, Tribes Hill, Y. Y. 

* Several specimens liave been sent to the collection without the localities 
having: been communicated to the writer. 

9 







66 


Report on Building Stones. 


51. Blue and Variegated Limestone. A finely dressed 
block of one cubic foot; from James Shanahan, Tribes 

Hill, Y. y. 

52. Gray Limestone. A dressed block of 14xlOJx6; 
from J. Critzer, Jacksonburgh, Y. Y. 

The four preceding specimens are from the Trenton 
limestone group. 

53. Dark Blue Limestone, Black Marble. A dressed 
and polished block of 12x7x6 inches, from the Howe’s 
Cave Lime and Cement Company, Cobleskill, Y. Y. 

54. Gray Variegated Limestone (Coral Marble). A 
polished slab of 8x32 inches, from the Hudson Coral 
Marble Company, Hudson, Y. Y. 

55. Gray Limestone, Gray Marble (Onondaga lime¬ 
stone). A dressed block of 9x9x9, with one face 
polished; from Mr. J. Hughes of Syracuse, Y. Y. 

56. White Marble. Lakeville, Connecticut. A rough 
block of 24x20x12 inches; from Wm. R. Smith of 
Athens, Y. Y. 

57. Blue Micaceous Limestone. Barrington, Mass. 
A rough block of about two and a half feet cube ; from 
Dr. Clarkson T. Collins. 


D . Sandstones or Freestones and Varieties of these 

Rocks. 

58. Brown Sandstone, Medina Sandstone. A dressed 
block of 12 x 12 x 9 inches ; from H. J. Sickles, Albion, 
Y. Y. 

59. Brown Sandstone. A finely dressed block of one 
cubic foot: Seneca Creek,Maryland; from Geo. Wrightson 
of Yew- York. 

60. Gray Sandstone. A dressed block of one cubic 
foot; from B. Clough, Plato, Ohio. 


Report on Building Stones. 


67 


61. Gray Sandstone. A dressed block of 12 x 17 x 17; 
from B. Clough, Plato, Ohio. 

62. Gray Sandstone. A dressed block or shaft of one 
foot square at base, and two feet nine inches high; from 
B. Clough, Plato, Ohio. 

63. Pine Gray Sandstone. Columbiana, Ohio; a finely 
dressed block-of one cubic foot: from B. Clough, Esq. 

64. Gray Sandstone. Specimen consisting of a dressed 
base of 12x12 inches and six inches high, surmounted 
by a cylindrical shaft of fifteen inches high and terminated 
by a carved rosette: Amherst, Ohio; from R. P. Wilson, 
ISTew York. 

65. Malden Blue Stone. A finely dressed block of 
12x8x5 inches, from the Bigelow Blue Stone Company, 
Malden, Y. Y. 

66. Hudson River Blue Stone. A dressed block of 
20x8x7 inches; from Benedict & Gill, Schenectady, 

Y. Y. 


GENERAL ABSTRACT OF CONTENTS OF REPORT. 


Preliminary Address. 

I. Granites, including Sienite, Gneiss or Gneissoid and Sienitic 

rocks; their Geological position and Geographical distri¬ 
bution. 

II. Marbles or Metamorphic crystalline limestones, their Geolo¬ 

gical position and Geographical distribution. 

III. Limestones not metamorphic, compactor sub-crystalline; their 

Geological position and Geographical distribution. 

IV. Sandstones or freestones, and their varieties; their Geological 

position and Geographical distribution within the State of 
New York. 

Y. On the selection of Buildiug Stones, and the causes of their 

YI. General composition and comparative durability of Building 
Stones. 

VII. Modes of determining the character and strength of Build¬ 

iug Stones. 

VIII. Causes affecting the durability of Building Stones, which are 

inherent in the Stone itself. 

IX. Causes affecting the durability of a stone, which are acci¬ 

dental, or due to artificial or extraneous conditions. 

X. Results of trials of the strength of various stones with tables 

of comparison for other stones. Incomplete. 

XI. Catalogue of the principal Stones in the Collection, which 

have been submitted to the commissioners for their inspec- . 
tion, or collected during the examination. 



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